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Fencer Vulns
high 7.5

CVE-2026-54789 json

mod_auth_openidc has out-of-bounds read and write in state cookie parsing

published 2026-08-21 2 mo ago modified 2026-10-15 24 d ago also EUVD-2026-64000

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

mod_auth_openidc is an OpenID Certified authentication and authorization module for the Apache 2.x HTTP server that implements the OpenID Connect Relying Party functionality. Prior to 2.4.19.4, an out-of-bounds read and a one-byte out-of-bounds write exist in the state-cookie parser of `mod_auth_openidc`. The issue is fixed in version 2.4.19.4 by stopping the scan at the string terminator so a value-less token is rejected. No in-product workarounds are available. As a stop-gap, an upstream reverse proxy or WAF that rejects or normalizes malformed `Cookie` headers (tokens lacking `=`) can reduce exposure, but upgrading is the recommended remediation.

Patch / fix

  • openidc mod_auth_openidc 2.4.19.4
  • libapache2-mod-auth-openidc Debian 12 2.4.12.3-2+deb12u5
  • libapache2-mod-auth-openidc Debian 13 2.4.17-1+deb13u1
  • libapache2-mod-auth-openidc Debian 14 2.4.19.4-1

debian advisories DEBIAN-CVE-2026-54789

  • mod_auth_openidc RHEL 9 2.4.16.11-1.el9_8.1
  • cjose RHEL 8 0.6.1-5.module+el8.10.0+24880+4db9166e
  • mod_auth_openidc RHEL 8 2.4.9.4-9.module+el8.10.0+24880+4db9166e
  • mod_auth_openidc RHEL 10.2 2.4.16.11-1.el10_2.1
  • mod_auth_openidc enterprise linux eus 10.0 2.4.15-4.el10_0.2
  • mod_auth_openidc RHEL 9.2 E4S 2.4.9.4-1.el9_2.4
  • cjose RHEL 8.8 TUS, RHEL 8.8 E4S 0.6.1-3.module+el8.8.0+19464+578f4546
  • mod_auth_openidc RHEL 8.8 TUS, RHEL 8.8 E4S 2.4.9.4-1.module+el8.8.0+24885+7d8e9f68.3

red hat advisories RHSA-2026:79177RHSA-2026:77369RHSA-2026:75581RHSA-2026:69719RHSA-2026:69720RHSA-2026:69717

  • apache2-mod_auth_openidc SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 2.4.17.1-150100.3.40.1
  • apache2-mod_auth_openidc SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Server Applications 15 SP7 2.4.17.1-150600.16.20.1
  • apache2-mod_auth_openidc SLES for SAP applications 16.0, SLES 16.0 2.4.17.1-160000.2.1
  • apache2-mod_auth_openidc SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.4.0-7.25.1

suse advisories SUSE-SU-2026:3953-1SUSE-SU-2026:3952-1SUSE-SU-2026:3915-1SUSE-SU-2026:23593-1

  • apache2-mod_auth_openidc openSUSE Leap 16.0 2.4.17.1-160000.2.1
  • apache2-mod_auth_openidc openSUSE Tumbleweed 2.4.20.2-1.1

opensuse advisories openSUSE-SU-2026:21717-1openSUSE-SU-2026:11582-1

  • mod_auth_openidc AlmaLinux 9 2.4.16.11-1.el9_8.1
  • cjose AlmaLinux 8 0.6.1-5.module_el8.10.0+4297+63ae3533
  • mod_auth_openidc AlmaLinux 8 2.4.9.4-9.module_el8.10.0+4297+63ae3533
  • mod_auth_openidc AlmaLinux 10 2.4.16.11-1.el10_2.1

almalinux advisories ALSA-2026:79177ALSA-2026:77369ALSA-2026:75581

  • mod_auth_openidc Rocky Linux 9 2.4.16.11-1.el9_8.1
  • cjose Rocky Linux 8 0.6.1-5.module+el8.10.0+40373+8a3f15d2
  • mod_auth_openidc Rocky Linux 8 2.4.9.4-9.module+el8.10.0+40373+8a3f15d2
  • mod_auth_openidc Rocky Linux 10 2.4.16.11-1.el10_2.1

rocky linux advisories RLSA-2026:79177RLSA-2026:77369RLSA-2026:75581

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-54789 updated cvss 7.5

mod_auth_openidc: mod_auth_openidc: Denial of Service via malformed state cookie parsing

  • Red Hat Enterprise Linux AppStream (v. 8) cjose 0.6.1-5.module+el8.10.0+24880+4db9166e, mod_auth_openidc 2.4.9.4-9.module+el8.10.0+24880+4db9166e
    fixed: vendor fix RHSA-2026:77369
  • Red Hat Enterprise Linux AppStream (v. 9) mod_auth_openidc 2.4.16.11-1.el9_8.1
    fixed: vendor fix RHSA-2026:79177
  • Red Hat Enterprise Linux AppStream (v. 10) mod_auth_openidc 2.4.16.11-1.el10_2.1
    fixed: vendor fix RHSA-2026:75581
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) cjose 0.6.1-3.module+el8.4.0+19462+14bde120, mod_auth_openidc 2.4.9.4-1.module+el8.4.0+24868+593d10ef.3
    fixed: vendor fix RHSA-2026:69712
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) cjose 0.6.1-3.module+el8.6.0+19463+7d2e1f9c, mod_auth_openidc 2.4.9.4-1.module+el8.6.0+24867+df0294a5.3
    fixed: vendor fix RHSA-2026:69713
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) cjose 0.6.1-3.module+el8.8.0+19464+578f4546, mod_auth_openidc 2.4.9.4-1.module+el8.8.0+24885+7d8e9f68.3
    fixed: vendor fix RHSA-2026:69717
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) mod_auth_openidc 2.4.9.4-1.el9_2.4
    fixed: vendor fix RHSA-2026:69720
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) mod_auth_openidc 2.4.9.4-4.el9_4.3
    fixed: vendor fix RHSA-2026:69718
show 6 more
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) mod_auth_openidc 2.4.15-4.el10_0.2
    fixed: vendor fix RHSA-2026:69719
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) mod_auth_openidc 2.4.10-1.el9_6.3
    fixed: vendor fix RHSA-2026:69716
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) cjose 0.6.1-3.module+el8.4.0+19462+14bde120, mod_auth_openidc 2.4.9.4-1.module+el8.4.0+24868+593d10ef.3
    fixed: vendor fix RHSA-2026:69712
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) cjose 0.6.1-3.module+el8.6.0+19463+7d2e1f9c, mod_auth_openidc 2.4.9.4-1.module+el8.6.0+24867+df0294a5.3
    fixed: vendor fix RHSA-2026:69713
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) cjose 0.6.1-3.module+el8.8.0+19464+578f4546, mod_auth_openidc 2.4.9.4-1.module+el8.8.0+24885+7d8e9f68.3
    fixed: vendor fix RHSA-2026:69717
  • Red Hat Enterprise Linux Server (v. 7 ELS) mod_auth_openidc 1.8.8-9.el7_9.2
    fixed: vendor fix RHSA-2026:69715

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • OpenIDC mod_auth_openidc

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.