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1.27.0 - OBO, Application-Level Rate Limiting and a Broad Security-Hardening Pass

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@aarora79 aarora79 released this 14 Jul 19:56
1.27.0
4c74a5a

Release 1.27.0 - OBO, Application-Level Rate Limiting and a Broad Security-Hardening Pass

July 2026

Overview

This release takes the per-user egress auth story most of the way there: both 3LO (per-user OAuth, tokens vaulted by the gateway) and OBO (on-behalf-of token exchange for same-trust-domain backends) are now fully implemented and work across providers. Direct PAT (personal access token) egress is still to come, so this is one big step closer rather than the finish line. On top of that, it adds more gateway-centric capabilities. With A2A reverse-proxy routing, you can now optionally route inter-agent (agent-to-agent) traffic through the gateway too, so agent calls get the same fine-grained access control (FGAC) governance we already apply to MCP servers, each agent gated per call with its own invoke_agent grant while its real backend stays private. And with application-level rate limiting, the gateway now does AI traffic management: identity-, group-, and target-aware request limits enforced at the auth-server hop, so you can cap a caller or protect a busy MCP server / A2A agent, complementary to the coarse per-IP edge limiting. The release also lands a broad security-hardening pass across the auth, proxy, data, and frontend layers.

Upgrading from 1.26.0

This section covers everything you need to know to upgrade from 1.26.0 to 1.27.0.

Breaking Changes

There are no breaking changes in this release. All new behavior is opt-in and defaults preserve the prior behavior:

  • Rate limiting is off by default (RATE_LIMITING_ENABLED=false). With it unset, /validate behaves exactly as before.
  • The registry configuration endpoints now require authentication. GET /api/config/* previously served without auth; it now requires a valid session/token. If you had tooling reading /api/config anonymously, give it an authenticated token. The anonymous /health probe no longer leaks deployment topology.
  • Internal service tokens are now single-use and M2M token audience is validated against an explicit allowlist. If you mint internal tokens outside the shipped flow, they must be single-use; M2M callers must present a token whose audience is allowlisted.

New Environment Variables

Variable Default Description
RATE_LIMITING_ENABLED false Master switch for application-level rate limiting. false = no checks (prior behavior).
RATE_LIMIT_BACKEND documentdb Counter backend. Only documentdb is implemented in v1.
RATE_LIMIT_FAIL_OPEN true Global fail-open on backend error (a per-limit fail_closed overrides to closed). Prevents a counter-store blip from becoming a full gateway outage.
RATE_LIMIT_DEFINITIONS_CACHE_TTL_SECONDS 30 In-process cache TTL for definition reads (zero DB reads in steady state).
RATE_LIMIT_BACKEND_TIMEOUT_MS 250 Hard per-op timeout for each counter operation, so a slow store fails fast into the fail-open/closed policy rather than hanging /validate.
RATE_LIMIT_USER_FLOOR_PER_MIN 20 Lockout-safeguard floor: a group whose short-window user limit falls below this is rejected at config time.
RATE_LIMIT_AGENT_FLOOR_PER_MIN 10 Lockout-safeguard floor for the agent (M2M) caller limit.
AUDIT_LOG_REQUIRE_DURABLE true Require the audit trail to be durable-by-default; a non-durable audit sink fails closed.
EGRESS_OBO_ALLOWED_AUDIENCES (empty) Explicit, audited allowlist of internal server audiences the OBO token-exchange may target. Empty denies OBO.
RUM_ALLOWED_HOSTS (empty) Comma-separated allowlist of hosts the RUM snippet may reference (script src + beacon). A snippet referencing any other host is rejected (fail closed). Empty disables RUM.
TRUSTED_PROXY_HOPS 1 Number of trusted reverse-proxy hops when resolving the client IP (rightmost-trusted XFF).
TRUSTED_EXTERNAL_HOSTS (empty) Allowlisted external Host values (e.g. a CloudFront domain) used when building redirect URIs.
TRUSTED_REAL_IP_CIDRS (empty) CIDRs of trusted upstreams (e.g. an ALB subnet) whose forwarded client IP is honored.
SSRF_ALLOWED_HOSTS (empty) Opt-in allowlist of internal hosts the SSRF guard may reach (for private A2A/MCP backends).
SSRF_ALLOWED_CIDRS (empty) Opt-in allowlist of internal CIDRs the SSRF guard may reach. Prefer SSRF_ALLOWED_HOSTS when you can name the hosts.

Rate-limit definitions and group memberships are managed at runtime (admin API /api/rate-limits, the rate-limit-* CLI commands, or Settings -> IAM -> Rate Limits in the UI), not via environment variables.

Upgrade Instructions

Docker Compose

cd mcp-gateway-registry
git pull origin main
git checkout 1.27.0

# Review new env vars in .env.example and update your .env if needed
# (rate limiting, SSRF allowlists, trusted-proxy, OBO audiences all default to
# prior behavior when unset). Then rebuild and restart:
./build_and_run.sh

Kubernetes / Helm (EKS)

cd mcp-gateway-registry
git pull origin main
git checkout 1.27.0

# REQUIRED: subchart templates/values changed in this release. Rebuild deps so
# the packaged .tgz subcharts pick up the changes (a plain helm upgrade would
# otherwise use the stale packaged subcharts).
cd charts/mcp-gateway-registry-stack
helm dependency build
helm dependency update

# Update values.yaml if needed (new rate-limiting, egress OBO, and
# trusted-request-source values), then upgrade:
helm upgrade mcp-gateway . -f your-values.yaml

Terraform / ECS

cd mcp-gateway-registry
git pull origin main
git checkout 1.27.0

# Update your .tfvars with any new variables (rate-limiting floors, SSRF
# allowlists, OBO audiences), then:
cd terraform/aws-ecs
terraform plan
terraform apply

Major Features

Application-Level Rate Limiting

Identity-, group-, and target-aware request limiting enforced at the auth-server /validate hop, complementary to the coarse per-IP nginx edge limiting. Two axes compose: a caller limit caps a user or agent (resolved by rate-limit group membership, kept in a dedicated collection and deliberately decoupled from the token's authz groups so adding a limit never changes a caller's scopes), and a target limit caps aggregate load on an MCP server or A2A agent regardless of caller. Each limit is per time window; multiple windows stack, and a request denied by a tighter window never consumes a wider window's quota. Lockout safeguards: admins bypass caller limits, caller limits apply to data-plane MCP/A2A calls only (never the dashboard or /api/*), and config-time floors reject a group whose short-window limit falls below the configured minimum. Counters live in DocumentDB (shared across replicas) via an atomic conditional increment; a per-op timeout fails fast into a fail-open availability guardrail by default, or fail-closed per-limit for security-critical caps. Throttled calls return HTTP 429 with X-RateLimit-* and Retry-After headers, plus an OTel metric and an attributable app-log line. Off by default; managed at runtime via the admin API, CLI, or the Settings -> IAM -> Rate Limits UI.

PR #1467

Amazon Cognito M2M (client_credentials) Support for Agent Callers

Agent (machine-to-machine) callers can now authenticate with Amazon Cognito client_credentials tokens, with provider-aware caller classification so a genuine M2M token is treated as an agent for rate limiting and authorization.

PR #1467

On-Behalf-Of (OBO) Egress Token Exchange

For same-trust-domain backends, the gateway now supports an obo_exchange egress mode (Microsoft Entra jwt-bearer today): it exchanges the caller's ingress token for a backend-audience token at call time, preserving the user's identity with nothing to vault. The target audiences are gated to an explicit, audited allowlist (EGRESS_OBO_ALLOWED_AUDIENCES). This complements the existing 3LO per-user vault, and 3LO itself now works across providers (including Entra).

PR #1420

A2A Reverse-Proxy Gateway Support

Opt in to route agent-to-agent traffic through the gateway the same way MCP servers are proxied: each enabled agent gets authenticated /agent/{path} routes, its real backend stays private (proxy_pass_url) and is redacted from non-admin reads, discovery advertises the gateway URL, and every call is gated per-agent with an invoke_agent grant. The egress trust model keeps the gateway a policy gate, not a credential broker: the caller's gateway token rides in X-Authorization (stripped at egress) while the target agent's own credential rides in Authorization (forwarded end to end).

PR #1355 · PR #1434

RFC 8707 Resource Indicator for Custom OAuth Providers

Custom OIDC egress providers can now emit an RFC 8707 resource indicator on the authorize request and both token grants, binding the minted token to one protected resource. This is required by resource servers that issue per-resource tokens (for example Atlassian's Rovo MCP).

PR #1427

What's New

Security Hardening

This release lands a broad, systematic security-hardening pass across the auth, proxy, data, and frontend layers:

  • OAuth CSRF hardening: validate the state at the token-exchange point (#1429)
  • Internal service tokens are now single-use to prevent replay (#1430)
  • Enforce M2M token audience against an explicit allowlist (#1418)
  • Require authentication for the registry configuration endpoints; stop leaking deployment topology from the anonymous /health probe (#1445)
  • Enforce scope-based server and tool access on the tool catalog and single-server reads (#1444)
  • Fix a skill-visibility bypass via cross-resource permission confusion (#1439)
  • Honor the disabled flag when enriching token groups from the database (#1443)
  • Authorization hardening: delete-ownership enforcement, path canonicalization before authz, credential-destination re-validation, group-enrichment gating, and token-mint session reconciliation (#1468)
  • Intra-admin safety guards and follow-up: refuse self-delete and last-admin removal/demotion (#1428, #1437)
  • Harden the audit trail: durable-by-default with per-instance attribution, and record raw human-readable identity across all audit streams (#1438, #1432)
  • Validate override endpoint fields through the canonical SSRF guard (#1470)
  • Close a potential regex-injection vector (#1417)
  • Tighten CLI credential handling (#1419)
  • Harden legacy static admin/privilege-granting tokens: validate strength, least-privilege federation scope (#1466, plus static-token bypass hardening)
  • AgentCore IAM scoping to least privilege (#1442)
  • Constrain auto-generated secret characters to a URI-safe, AWS-safe set (#1362)
  • Add a repository security-guidelines catalog and wire it into the review skills (#1416)

Infrastructure and Deployment

  • CDK / Terraform parity: embed CloudFront, drop the 8888/7860 listeners, sslRequired=external (#1435)
  • Fix DocumentDB rotation IAM to use the rds:* action namespace the boto3 docdb client actually evaluates, in both Terraform and CDK (#1406, #1474)
  • Generic bring-your-own RUM (Real User Monitoring) injection hook for the frontend, host-allowlisted and fail-closed (#1472)
  • Configurable Claude Code connect-snippet scope via IDE_CONNECT_SCOPE (#1464)
  • nginx edge rate limiting (#1431)

Frontend

  • Page through the list APIs so the dashboard is not hard-capped at the first page (#1436)

Documentation

  • New 3LO (per-user OAuth) AgentCore gateway FAQ, with a Cognito + Claude Code worked example (#1473)
  • Correct the egress runtime-sequence diagram to match the implementation (#1483)
  • README refactor: audience-routed rewrite, theory-of-the-system and executive brief, feature/release highlights, and MkDocs strict-mode nav cleanup (#1422, #1423, #1424, #1425)
  • Move release notes out of the main README into the docs site (#1411, #1421)
  • Update the 3LO demo video link across docs and README (#1482)

CI and Maintenance

  • Align the repository to pre-commit and enforce it (#1440)
  • Use a slim detect-secrets baseline to stop line-number churn (#1480)
  • Use the lockfile for docs builds (#1465)
  • Weekly dependency and GitHub Actions updates (#1408, #1409, #1462, #1463)

Bug Fixes

  • fix(scopes): grant publish_skill to the admin seed scopes (#1479)
  • fix(a2a): pass a dict to update_agent in the security-pending-tag path (#1441)
  • fix(rate-limiting): provider-aware caller classification, correct human-vs-agent classification, surface throttle as 429 through nginx auth_request, and capture the actual Retry-After header (#1467)
  • fix(readme): replace the PAT-gated star-history chart with shields.io badges (#1481)

Closed Issues

Issue Title Closed By
#1471 Add a generic RUM injection hook for the frontend PR #1472
#1433 Failed to get admin token (admin publish_skill permission) PR #1479
#1410 Remove "What's New" from README.md PR #1411
#1354 Auto-generated secrets with special characters break deployment PR #1362
#1348 DocumentDB secret rotation fails: docdb:* vs rds:* namespace PR #1406
#1282 SSRF hardening: validate outbound URL on agent card fetch PR #1470
#1269 Egress: token-exchange (OBO) for same-trust-domain backends PR #1420
#880 Implement proper frontend pagination for servers, agents, skills PR #1436
#847 Add reverse-proxy gateway support for A2A agents PR #1355
#295 Application-level rate limiting PR #1467

Pull Requests Included

PR Title
#1483 docs: correct egress runtime-sequence diagram to match implementation
#1482 docs: update 3LO demo video link across docs and README
#1481 fix(readme): replace PAT-gated star-history chart with shields.io badges
#1480 chore(ci): use slim detect-secrets baseline to stop line-number churn
#1479 fix(scopes): grant publish_skill to admin seed scopes
#1474 fix(cdk): use rds:* actions for DocumentDB rotation IAM (Terraform parity)
#1473 docs: add FAQ for 3LO (per-user OAuth) AgentCore gateways
#1472 Add generic bring-your-own RUM hook for the frontend
#1470 Validate override endpoint fields through the canonical SSRF guard
#1469 chore(usage-report): bump install-forecast target to 2,000
#1468 Authorization hardening: delete ownership, path canonicalization, credential re-validation, enrichment gating, mint reconciliation
#1467 feat: application-level rate limiting + Cognito M2M support
#1466 Harden legacy static admin token
#1465 use lockfile for docs builds
#1464 feat(connect): configurable Claude Code snippet scope (IDE_CONNECT_SCOPE)
#1463 chore(deps): weekly lockfile update (2026-07-13)
#1462 build(deps): bump the actions group with 7 updates
#1445 Require authentication for the registry configuration
#1444 Enforce scope-based server and tool access on the tool catalog and single-server reads
#1443 Honor the disabled flag when enriching token groups from the database
#1442 Agentcore scoping
#1441 fix(a2a): pass dict to update_agent in security-pending-tag path
#1440 fix: align repository to pre-commit and enforce pre-commit
#1439 Fix skill visibility bypass via cross-resource permission confusion
#1438 Harden the audit trail: durable-by-default and per-instance attribution
#1437 admin safety guards followup
#1436 fix(frontend): page through list APIs so dashboard is not hard-capped
#1435 feat(infra): CDK / Terraform parity, embed CloudFront, drop 8888/7860 listeners
#1434 feat(a2a): egress trust model, {agent,actions} scopes, gateway-aware discovery
#1432 fix(audit): record raw human-readable identity across all audit streams
#1431 nginx rate limiting
#1430 Make internal service tokens single-use
#1429 OAuth CSRF Hardening
#1428 Intra-admin safety guards
#1427 feat(egress): add RFC 8707 resource indicator for custom OAuth providers
#1425 docs: replace MkDocs site with a README-generated landing page
#1424 docs: fix all mkdocs --strict warnings and auto-generate nav
#1423 docs: rewrite README (audience-routed) + regrowth prevention
#1422 docs: add theory-of-the-system, executive brief, and feature/release highlights
#1421 Add redirect stubs for moved release notes; fix stale path references
#1420 Egress OBO: add obo_exchange mode + make 3LO work on Entra / across providers
#1419 tighten cli credentials
#1418 Enforce M2M token audience against an explicit allowlist
#1417 close potential regex injection
#1416 add security guidelines
#1413 docs(skills): add security-patterns catalog and wire into review skills
#1412 skill credential handling
#1411 remove releases notes from main repo README and add to mkdocs
#1409 chore(deps): weekly lockfile update (2026-07-06)
#1408 build(deps): bump the actions group with 7 updates
#1406 Fix DocumentDB rotation IAM actions
#1362 fix: constrain secret characters to URI-safe, AWS-safe set
#1355 feat(a2a): add reverse-proxy gateway support for A2A agents

Contributors

Thank you to all contributors for this release:

Support

Full Changelog: 1.26.0...1.27.0

What's Changed

  • build(deps): bump the actions group in /.github/workflows with 7 updates by @dependabot[bot] in #1408
  • chore(deps): weekly lockfile update (2026-07-06) by @github-actions[bot] in #1409
  • docs(skills): add security-patterns catalog and wire into review skills by @aarora79 in #1413
  • fix: constrain secret characters to URI-safe, AWS-safe set (#1354) by @zsxh1990 in #1362
  • skill credential handling by @omrishiv in #1412
  • add security guidelines by @omrishiv in #1416
  • close potential regex injection by @omrishiv in #1417
  • Enforce M2M token audience against an explicit allowlist by @omrishiv in #1418
  • remove releases notes from main repo README and add to mkdocs by @ceng-p in #1411
  • Add redirect stubs for moved release notes; fix stale path references (follow-up to #1411) by @aarora79 in #1421
  • docs: add theory-of-the-system, executive brief, and feature/release highlights (README refactor, PR A) by @aarora79 in #1422
  • docs: rewrite README (audience-routed, ~130 lines) + regrowth prevention (README refactor, PR B) by @aarora79 in #1423
  • docs: fix all mkdocs --strict warnings and auto-generate nav via awesome-pages by @aarora79 in #1424
  • docs: replace MkDocs site with a README-generated landing page + restore fork-safe relative links by @aarora79 in #1425
  • tighten cli credentials by @omrishiv in #1419
  • OAuth CSRF Hardening by @omrishiv in #1429
  • Egress OBO: add obo_exchange mode + make 3LO work on Entra / across providers by @omrishiv in #1420
  • fix(audit): record raw human-readable identity across all audit streams by @omrishiv in #1432
  • Intra-admin safety guards by @omrishiv in #1428
  • admin safety guards followup by @omrishiv in #1437
  • Make internal service tokens single-use by @omrishiv in #1430
  • nginx rate limiting by @omrishiv in #1431
  • Fix skill visibility bypass via cross-resource permission confusion by @omrishiv in #1439
  • Harden the audit trail: durable-by-default and per-instance attribution by @omrishiv in #1438
  • feat(a2a): add reverse-proxy gateway support for A2A agents by @anjosluc in #1355
  • feat(a2a): egress trust model, {agent,actions} scopes, gateway-aware discovery by @aarora79 in #1434
  • fix(a2a): pass dict to update_agent in security-pending-tag path by @aarora79 in #1441
  • fix: align repository to pre-commit and enforce pre-commit by @omrishiv in #1440
  • feat(infra): CDK ↔ Terraform parity — embed CloudFront, drop 8888/7860 listeners, sslRequired=external by @harshitkgupta in #1435
  • Honor the disabled flag when enriching token groups from the database by @omrishiv in #1443
  • Enforce scope-based server and tool access on the tool catalog and single-server reads by @omrishiv in #1444
  • Require authentication for the registry configuration by @omrishiv in #1445
  • feat(egress): add RFC 8707 resource indicator for custom OAuth providers by @go-faustino in #1427
  • chore(deps): weekly lockfile update (2026-07-13) by @github-actions[bot] in #1463
  • use lockfile for docs builds by @omrishiv in #1465
  • chore(deps): bump the actions group in /.github/workflows with 7 updates by @dependabot[bot] in #1462
  • Harden legacy static admin token by @omrishiv in #1466
  • feat(connect): configurable Claude Code snippet scope (IDE_CONNECT_SCOPE) by @go-faustino in #1464
  • feat: application-level rate limiting + Cognito M2M support (#295) by @aarora79 in #1467
  • chore(usage-report): bump install-forecast target to 2,000 by @aarora79 in #1469
  • Agentcore Scoping by @omrishiv in #1442
  • fix(frontend): page through list APIs so dashboard is not hard-capped (#880) by @KhaiTrang1995 in #1436
  • Validate override endpoint fields through the canonical SSRF guard by @omrishiv in #1470
  • Add generic bring-your-own RUM hook for the frontend (#1471) by @aarora79 in #1472
  • docs: add FAQ for 3LO (per-user OAuth) AgentCore gateways by @aarora79 in #1473
  • Fix DocumentDB rotation IAM actions by @ahfoysal in #1406
  • fix(cdk): use rds:* actions for DocumentDB rotation IAM (Terraform parity) by @aarora79 in #1474
  • Authorization hardening: delete ownership, path canonicalization, credential re-validation, enrichment gating, mint reconciliation by @omrishiv in #1468
  • fix(scopes): grant publish_skill to admin seed scopes (#1433) by @aarora79 in #1479
  • chore(ci): use slim detect-secrets baseline to stop line-number churn by @aarora79 in #1480
  • fix(readme): replace PAT-gated star-history chart with shields.io badges by @aarora79 in #1481
  • docs: update 3LO demo video link across docs and README by @aarora79 in #1482
  • docs: correct egress runtime-sequence diagram to match implementation by @aarora79 in #1483

New Contributors

Full Changelog: 1.26.0...1.27.0

Contributors

omrishiv, harshitkgupta, and 8 other contributors
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