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Advisory severityHigh7.5Red Hat Linux

High [CVE-2025-3891] Mod_auth_openidc: dos via empty post in mod_auth_openidc with oidcpreservepost enabled

This high-severity Red Hat Linux advisory covers CVE-2025-3891 affecting Red Hat Enterprise Linux 8.2 Advanced Update Support, Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support, Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2025-3891 Source published Source updated

VulniPulse record published

CVE-2025-3891
Affected products & platforms
Red Hat LinuxRed Hat Enterprise Linux
Open source advisory

Summary

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. Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Weakness: CWE-248.

Affected Red Hat products: Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 8.2 Advanced Update Support; Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.6 Telecommunications Update Service; Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions; Red Hat Enterprise Linux 8.8 Telecommunications Update Service; Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.4 Extended Update Support; Red Hat Enterprise Linux 10.

Red Hat lists Red Hat Enterprise Linux 7 as not affected. Red Hat fixing advisory: RHSA-2025:4597, RHSA-2025:10006, RHSA-2025:10004, RHSA-2025:10003, RHSA-2025:10010, RHSA-2025:9396, RHSA-2025:10002, RHSA-2025:10008, RHSA-2025:10007.

Is CVE-2025-3891 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2025-3891 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2025-3891?

Upgrade to a fixed release named by Red Hat:

  • mod_auth_openidc:2.3-8100020250426100353.489197e6
  • mod_auth_openidc:2.3-8020020250612174445.4cda2c84
  • mod_auth_openidc:2.3-8040020250618101351.522a0ee4
  • mod_auth_openidc:2.3-8060020250617090503.ad008a3a
  • mod_auth_openidc:2.3-8080020250617090716.63b34585
  • mod_auth_openidc-0:2.4.10-1.el9_6.2
  • mod_auth_openidc-0:2.4.9.4-1.el9_0.3
  • mod_auth_openidc-0:2.4.9.4-1.el9_2.3
  • mod_auth_openidc-0:2.4.9.4-4.el9_4.2
  • RHSA-2025:4597
  • RHSA-2025:10006
  • RHSA-2025:10004

6 more fixed releases are listed below.

Confirm against the vendor advisory before you patch.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Fixed versions
  • mod_auth_openidc:2.3-8100020250426100353.489197e6
  • mod_auth_openidc:2.3-8020020250612174445.4cda2c84
  • mod_auth_openidc:2.3-8040020250618101351.522a0ee4
  • mod_auth_openidc:2.3-8060020250617090503.ad008a3a
  • mod_auth_openidc:2.3-8080020250617090716.63b34585
  • mod_auth_openidc-0:2.4.10-1.el9_6.2
  • mod_auth_openidc-0:2.4.9.4-1.el9_0.3
  • mod_auth_openidc-0:2.4.9.4-1.el9_2.3
  • mod_auth_openidc-0:2.4.9.4-4.el9_4.2
  • RHSA-2025:4597
  • RHSA-2025:10006
  • RHSA-2025:10004
  • RHSA-2025:10003
  • RHSA-2025:10010
  • RHSA-2025:9396
  • RHSA-2025:10002
  • RHSA-2025:10008
  • RHSA-2025:10007

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Mitigation

Upgrade to a fixed release: mod_auth_openidc:2.3-8100020250426100353.489197e6, mod_auth_openidc:2.3-8020020250612174445.4cda2c84, mod_auth_openidc:2.3-8040020250618101351.522a0ee4, mod_auth_openidc:2.3-8060020250617090503.ad008a3a, mod_auth_openidc:2.3-8080020250617090716.63b34585, mod_auth_openidc-0:2.4.10-1.el9_6.2. That is the remediation for this advisory.

The vendor advisory may list interim mitigations or workarounds not captured here. Review it before change work.

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

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