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.

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.

Impact

An issue in DigestAuthProvider.verify:

Algorithm silently forced to MD5. The configured algorithm parameter was ignored — every verification used MD5 regardless of configuration. Deployments believing they were running SHA-256 Digest auth were silently inheriting MD5's collision weaknesses, including documented attack paths against Digest schemes that rely on the hash being collision-resistant.

Who is affected: any application using http4k-security-digest for HTTP Digest authentication. The bug has been present since DigestAuthProvider was introduced (commit 8a52b615b1, 2021).

Patches

| Line | Fixed in | Edition | |------|----------|---------| | v6.x (Community) | 6.50.0.0 | Community | | v5.x (LTS) | 5.42.0.0 | Enterprise — contact [email protected] (if Digest auth is present in your v5.x line) | | v4.x (LTS) | 4.51.0.0 | Enterprise — contact [email protected] (if Digest auth is present in your v4.x line) |

The fix:

• Hashes with the configured algorithm instead of hardcoded MD5.

Workarounds

For deployments that cannot upgrade immediately:

• Algorithm gap: do not rely on algorithm configuration; assume MD5 is in use and treat the Digest credentials as low-trust.

References

• Vulnerability first present: 8a52b615b1
• Algorithm fix: 65d23d99fc
• Fix release: v6.50.0.0
• Background: RFC 7616 — HTTP Digest Access Authentication

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.

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.

Impact

An issue in DigestAuthProvider.verify:

Algorithm silently forced to MD5. The configured algorithm parameter was ignored — every verification used MD5 regardless of configuration. Deployments believing they were running SHA-256 Digest auth were silently inheriting MD5's collision weaknesses, including documented attack paths against Digest schemes that rely on the hash being collision-resistant.

Who is affected: any application using http4k-security-digest for HTTP Digest authentication. The bug has been present since DigestAuthProvider was introduced (commit 8a52b615b1, 2021).

Patches

| Line | Fixed in | Edition | |------|----------|---------| | v6.x (Community) | 6.50.0.0 | Community | | v5.x (LTS) | 5.42.0.0 | Enterprise — contact [email protected] (if Digest auth is present in your v5.x line) | | v4.x (LTS) | 4.51.0.0 | Enterprise — contact [email protected] (if Digest auth is present in your v4.x line) |

The fix:

• Hashes with the configured algorithm instead of hardcoded MD5.

Workarounds

For deployments that cannot upgrade immediately:

• Algorithm gap: do not rely on algorithm configuration; assume MD5 is in use and treat the Digest credentials as low-trust.

References

• Vulnerability first present: 8a52b615b1
• Algorithm fix: 65d23d99fc
• Fix release: v6.50.0.0
• Background: RFC 7616 — HTTP Digest Access Authentication