CVE-2026-54147

http4k is a functional toolkit for Kotlin HTTP applications. Prior to 4.51.0.0, 5.42.0.0, and 6.50.0.0, DigestAuthProvider.verify in http4k-security-digest ignores its configured algorithm parameter and verifies every Digest response with hardcoded MD5. Deployments configured for SHA-256 therefore receive weaker MD5-based verification, exposing Digest authentication to collision-related attack paths that depend on the hash function's collision resistance. This issue is fixed in versions 4.51.0.0, 5.42.0.0, and 6.50.0.0.

• https://github.com/http4k/http4k/commit/65d23d99fc5afbe34f29d8f61d0a003fbebb381c
• https://github.com/http4k/http4k/releases/tag/6.50.0.0
• https://github.com/http4k/http4k/security/advisories/GHSA-vxxm-wwqh-mh47