# CVE-2026-100834: http4k Digest authentication nonce verification bypass

Source: https://junglewise.ai/threats/cve-2026-100834-http4k-s-digest-authentication-module-org-http4k-http4k-security  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-27. Updated: 2026-09-27  
License: CC BY 4.0 with a link back

CVE-2026-100834 · Severity: medium · CVSS 5.9 · Published 2026-09-27

http4k's Digest authentication security module defaults to accepting all authentication nonces without validation. This allows attackers who capture a valid Digest authentication response from network traffic or logs to replay it indefinitely against protected resources, bypassing intended replay attack protection and potentially gaining unauthorized access.

Technologies: [Http4k-Security-Digest](https://junglewise.ai/threats/technologies/http4k-security-digest). Vendors: [Http4k](https://junglewise.ai/threats/vendors/http4k).

## Quick answers

**Is CVE-2026-100834 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100834 being exploited in the wild.

**How severe is CVE-2026-100834?** Medium severity, with a CVSS score of 5.9, published 27 September 2026.

**Which products and versions are affected?** Http4k-Security-Digest before 4.51.0.0, 5.42.0.0, and 6.48.0.0.

**Is there a fix for CVE-2026-100834?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-100834 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-100834?** Check whether you run Http4k-Security-Digest at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The nonceVerifier parameter in ServerFilters.DigestAuth and DigestAuthProvider defaults to accepting all nonces (always returns true), eliminating replay protection. An attacker can reuse a captured Authorization header indefinitely without network access required beyond initial sniffing. The fix requires explicitly configuring a proper nonce verifier; versions 4.51.0.0, 5.42.0.0, and 6.48.0.0 remove the unsafe default.

## Affected products

- http4k http4k-security-digest before 4.51.0.0, 5.42.0.0, and 6.48.0.0

## Timeline

- 2026-09-27: disclosed

## References

- [https://github.com/http4k/http4k/commit/4f904b4692](https://github.com/http4k/http4k/commit/4f904b4692)
- [https://github.com/http4k/http4k/commit/8a52b615b1](https://github.com/http4k/http4k/commit/8a52b615b1)

## Related threats

- [http4k Digest authentication missing body integrity in auth-int](https://junglewise.ai/threats/cve-2026-120317-http4k-from-4-9-10-0-before-6-60-0-0-contains-a-missing)
- [http4k http4k-security-digest weak cryptographic algorithm in DigestAuthProvider](https://junglewise.ai/threats/cve-2026-54147-http4k-http4k-security-digest-weak-cryptographic-algorithm-in)
- [http4k disabled replay protection in Digest authentication default configuration](https://junglewise.ai/threats/http4k-disabled-replay-protection-in-digest-authentication-default-7947f267)