CVE-2026-54147

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 enterprise@http4k.org (if Digest auth is present in your v5.x line)
v4.x (LTS)	4.51.0.0	Enterprise — contact enterprise@http4k.org (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