What’s Vulnerable › Vulnerabilities

CVE-2026-100834: http4k before 6.48.0.0 Digest Authentication Replay Protection Bypass

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-27 · updated 2026-10-29
• Weakness: CWE-294

Description

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.

Affected products

• http4k: from 6.0.0.0 before 6.48.0.0 — fixed in 6.48.0.0

How to fix

Upgrade to a fixed version: http4k 6.48.0.0. Check the vendor advisory for mitigations.

References

• https://github.com/http4k/http4k/commit/4f904b4692
• https://github.com/http4k/http4k/commit/8a52b615b1
• https://github.com/http4k/http4k/security/advisories/GHSA-c7jm-38gq-h67h
• https://www.vulncheck.com/advisories/http4k-before-6.48.0.0-digest-authentication-replay-protection-bypass

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