Add TLS Supported Groups (tls_groups) to Nuclei SSL Templates

[goosvorbook]

Hi ProjectDiscovery team,

I'd like to propose exposing configurable TLS Supported Groups in Nuclei's native SSL protocol templates.

This would enable more accurate TLS key exchange testing, particularly for Post-Quantum Cryptography (PQC) readiness and Harvest Now, Decrypt Later (HNDL) exposure assessments.

The problem

Nuclei's SSL protocol currently allows template authors to configure TLS versions and cipher suites, but not the TLS Supported Groups offered during the handshake.

This is important because TLS 1.3 cipher suites do not identify the negotiated key exchange mechanism.

For example, a TLS 1.3 connection using TLS_AES_128_GCM_SHA256 could negotiate either:

• X25519 — classical key exchange
• X25519MLKEM768 — hybrid post-quantum key exchange

Simply observing the negotiated key exchange does not establish which other groups the server supports.

Existing TLSX implementation

TLSX already supports explicitly configuring TLS Supported Groups through the -tls-groups (-tg) option.

This functionality was implemented in:

projectdiscovery/tlsx#1010

For example:

tlsx -u example.com -sm ctls -tg X25519MLKEM768 -j
tlsx -u example.com -sm ctls -tg X25519 -j

These commands allow controlled testing of hybrid PQC support and classical key exchange compatibility.

However, Nuclei's native SSL protocol does not currently expose an equivalent configuration option.

Proposed enhancement

Would it be possible to introduce a tls_groups field in Nuclei's SSL protocol?

For example:

id: tls-hybrid-kex-detect

info:
  name: TLS Hybrid Key Exchange - Detect
  author: example
  severity: info
  tags: ssl,tls,pqc

ssl:
  - address: "{{Host}}:{{Port}}"
    scan_mode: ctls
    min_version: tls13
    max_version: tls13

    tls_groups:
      - X25519MLKEM768

    matchers:
      - type: dsl
        condition: and
        dsl:
          - 'probe_status == true'
          - 'tls_version == "tls13"'
          - 'key_exchange == "X25519MLKEM768"'

Note: This is proposed syntax, not a currently supported Nuclei template.

Ideally, the implementation would reuse the existing TLSX clients.Options.TLSGroups functionality.

Expected behavior

• Allow one or more TLS Supported Groups to be specified per SSL request.
• Forward these groups to TLSX.
• Support constrained group testing through the ctls backend.
• Reject invalid or unsupported group names

[goosvorbook]

Relationship to Nuclei PR #7680

I noticed that PR #7680 recently introduced negotiated TLS key exchange metadata:

#7680

This is a great addition and provides exactly the response-side visibility needed for PQC assessments.

However, the PR explicitly states that no TLS configuration or handshake behavior is changed.

The proposed tls_groups enhancement would complement this work by adding request-side control over the offered TLS Supported Groups, allowing template authors to test specific classical and hybrid post-quantum key exchanges rather than only observing the group selected during a default handshake.

In short:

• PR feat (http) : expose TLS key exchange metadata #7680: Observe the negotiated key exchange.
• This proposal: Control which key exchange groups are offered.

Together, these capabilities would enable reliable native Nuclei templates for PQC migration and HNDL assessments.