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.

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

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. 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

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