CVE-2026-54147: HTTP4K

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• HTTP4K HTTP4K: before 4.51.0.0 (fixed in 4.51.0.0); from 5.0.0.0, before 5.42.0.0 (fixed in 5.42.0.0); from 6.0.0.0, before 6.50.0.0 (fixed in 6.50.0.0)

Published 2026-09-18. Last modified 2026-09-24.