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.
Affected products
apache: http server; redhat: enterprise linux; debian: debian linux
References10
- access.redhat.com/errata/RHSA-2025:10002
- access.redhat.com/errata/RHSA-2025:10003
- access.redhat.com/errata/RHSA-2025:10004
- access.redhat.com/errata/RHSA-2025:10006
- access.redhat.com/errata/RHSA-2025:10007
- access.redhat.com/errata/RHSA-2025:10008
- access.redhat.com/errata/RHSA-2025:10010
- access.redhat.com/errata/RHSA-2025:4597 Third Party Advisory
- access.redhat.com/errata/RHSA-2025:9396
- access.redhat.com/security/cve/CVE-2025-3891 Third Party Advisory
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 2% percentile: 76 · as of 7 November 2026
- CWE
- CWE-248
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.