Vulnerability in Http4k
CVE-2026-100834
http4k's Digest authentication module (org.http4k:http4k-security-digest) before versions 6.48.0.0, 5.42.0.0 and 4.51.0.0 defaults the nonceVerifier parameter of ServerFilters.DigestAuth and DigestAuthProvider to { true }, so every nonce is accepted regardless of its value, age, or prior use. Applications relying on this default have no replay protection on Digest authentication: an attacker who can capture a valid 'Authorization: Digest' response (for example by observing network traffic or reading logs) can replay it indefinitely against the same protected resource.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (25.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
Weakness classification (CWE)
References
- GitHub Security Advisory (GHSA-c7jm-38gq-h67h) (vendor-advisory)
- Patch Commit (patch)
- Patch Commit (patch)
- VulnCheck Advisory: http4k before 6.48.0.0 Digest Authentication Replay Protection Bypass (third-party-advisory)
Frequently asked questions
- What is CVE-2026-100834?
- CVE-2026-100834 is a medium-severity vulnerability in Http4k, classified under Authentication Bypass by Capture-replay. CVSS score: 5.9/10. Published 2026-09-27.
- How severe is CVE-2026-100834?
- Medium severity. CVSS v3 base score is 5.9 out of 10.