fix(webhook): validate custom headers as a control-char-free string map - #403
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The webhook `headers` field was only @isObject — it accepted any shape with no per-value validation, so a value containing CR/LF could attempt header injection into the outbound request and non-string values silently broke delivery. Add an @IsHeaderMap validator (Create + Update DTOs) that requires valid header names, string values free of C0 control chars (the CR/LF injection vector), and bounds the map (max 50 entries, value max 1024 chars). The delivery-time reserved-name filter (sanitizeCustomHeaders) is unchanged.
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Summary
The webhook
headersfield (Create + Update DTOs) was validated only with@IsObject()— it accepted any object shape with no per-entry checks. That allowed:CR/LF(e.g."a\r\nX-Injected: 1") could attempt to inject extra headers into the outbound webhook request.A new
@IsHeaderMap()validator now requires a flat map of valid header names ([A-Za-z0-9-]+) to string values that are free of C0 control characters + DEL, and bounds the map (≤50 entries, value ≤1024 chars). The existing delivery-time reserved-name filter (sanitizeCustomHeaders) is unchanged — this is the complementary input-side guard.Tests
webhook.dto.spec.ts: accepts a normal string map; rejects CR/LF values (injection), non-string values, invalid header names;UpdateWebhookDtoenforces the same.Risk
Low. Only rejects header maps that were already malformed or unsafe at delivery — surfaces the error at create/update time (400) instead of silently mangling or injecting at send time. Valid string headers are unaffected.