CVE-2026-54147 http4k: `DigestAuthProvider.verify` ignored configured algorithm and did not bind to request URI
Digest authentication verification ignores configured algorithms, forcing weak MD5 usage and enabling collision-based attacks against deployments expecting stronger hashing.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54147?
CVE-2026-54147 is a medium-severity vulnerability in http4k, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-327
Which versions are affected by CVE-2026-54147?
6 open source packages ship an affected version, including org.http4k:http4k-security-digest.
| Package | Affected | Fixed in |
|---|---|---|
org.http4k:http4k-security-digest Maven | All versions to 4.48.2.0 | None |
org.http4k:http4k-security-digest Maven | All versions to 4.48.2.0 | None |
org.http4k:http4k-security-digest Maven | From 5.0.0.0 | 5.42.0.0 |
org.http4k:http4k-security-digest Maven | From 5.0.0.0 | 5.42.0.0 |
org.http4k:http4k-security-digest Maven | From 6.0.0.0 | 6.50.0.0 |
org.http4k:http4k-security-digest Maven | From 6.0.0.0 | 6.50.0.0 |
How do I fix CVE-2026-54147?
Upgrade org.http4k:http4k-security-digest to a fixed version for your release line: 5.42.0.0 or 6.50.0.0.
Is CVE-2026-54147 being exploited?
There is no known exploitation of CVE-2026-54147 in the wild and no public exploit code.
Sources
Also known as GHSA-vxxm-wwqh-mh47.