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TI-2026-59953 Aliases CVE-2026-87853GHSA-993g-jgf7-rg3x

Sssd: sssd: idp authentication prefix comparison allows cross-user impersonation

Priority LOW 35CWE-187Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 3 fixed, 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

A flaw was found in SSSD's IdP authentication provider. The eval_access_token_buf() function compares the OIDC subject identifier using strncmp() with the authenticated user's identifier length, performing a prefix comparison instead of an exact match. An attacker whose IdP identifier is a strict prefix of a target user's identifier can authenticate as the target user.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00328 26th percentileScored 2026-11-07
Fix Partial Red Hat: 1 advisoryRed Hat: 3 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Red HatRed Hat Enterprise Linux 10—2.12.0-3.el10_2.2Patch availableCNA
Red HatRed Hat Enterprise Linux 6——No fix listedCNA
Red HatRed Hat Enterprise Linux 7——Not affectedCNA
Red HatRed Hat Enterprise Linux 8——Not affectedCNA
Red HatRed Hat Enterprise Linux 9——Not affectedCNA
Red HatRed Hat OpenShift Container Platform 4——Not affectedCNA
Red HatRed Hat OpenShift Container Platform 4——Not affectedCNA
Red HatRed Hat OpenShift Container Platform 5——Not affectedCNA
  • Red Hat Enterprise Linux 10 VendorRed Hat Affected — Fixed in 2.12.0-3.el10_2.2 Patch available CNA
  • Red Hat Enterprise Linux 6 VendorRed Hat Affected — Fixed in — No fix listed CNA
  • Red Hat Enterprise Linux 7 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat OpenShift Container Platform 5 VendorRed Hat Affected — Fixed in — Not affected CNA

CPE names CNA · 7

CPEVersionsRoleVendor
cpe:/o:redhat:enterprise_linux:10.210.2—Red Hat
cpe:/o:redhat:rhel_els:66—Red Hat
cpe:/o:redhat:rhel_els:77—Red Hat
cpe:/a:redhat:enterprise_linux:88—Red Hat
cpe:/a:redhat:enterprise_linux:99—Red Hat
cpe:/a:redhat:openshift:44—Red Hat
cpe:/a:redhat:openshift:55—Red Hat
  • cpe:/o:redhat:enterprise_linux:10.2 Versions 10.2 — ·Red Hat
  • cpe:/o:redhat:rhel_els:6 Versions 6 — ·Red Hat
  • cpe:/o:redhat:rhel_els:7 Versions 7 — ·Red Hat
  • cpe:/a:redhat:enterprise_linux:8 Versions 8 — ·Red Hat
  • cpe:/a:redhat:enterprise_linux:9 Versions 9 — ·Red Hat
  • cpe:/a:redhat:openshift:4 Versions 4 — ·Red Hat
  • cpe:/a:redhat:openshift:5 Versions 5 — ·Red Hat

Remediation

Red Hat 1 advisory

  • RHSA-2026:77534 Released 2026-10-08 · Red Hat rating Moderate
    sssd security update
    • Red Hat Enterprise Linux AppStream (v. 10) sssd-idp-2.12.0-3.el10_2.2
    • Red Hat Enterprise Linux BaseOS (v. 10) libipa_hbac-2.12.0-3.el10_2.2, libsss_autofs-2.12.0-3.el10_2.2, libsss_certmap-2.12.0-3.el10_2.2 +24
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libsss_nss_idmap-devel-2.12.0-3.el10_2.2

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:77534
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:77534
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:77534
Not affected: 5 products
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat OpenShift Container Platform 4
  • Red Hat OpenShift Container Platform 5

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-87853
  2. 2026-10-03 Alias added: GHSA-993g-jgf7-rg3x
  3. 2026-10-09 Fix available: RHSA-2026:77534 · Red Hat
  4. 2026-10-09 Fix available: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · Red Hat
  5. 2026-10-09 Fix available: sssd@0:2.12.0-3.el10_2.2 · CNA
  6. 2026-10-09 1 new reference · CNA
  7. 2026-10-21 Affected versions changed · CNA
  8. 2026-10-22 Affected versions changed · Red Hat
  9. 2026-10-29 Affected versions changed · CNA
  10. 2026-10-29 Affected versions changed · Red Hat
  11. 2026-11-03 Affected versions changed · CNA
  12. 2026-11-03 Affected versions changed · Red Hat

References

Advisory 1

Other 2

  • TI-2019-15875 Protection mechanism failure in Jenkins Pipeline: Groovy Plugin KEVCVSS 3.1CRITICAL 9.9
  • TI-2019-15874 Protection mechanism failure in Jenkins Script Security Plugin KEVCVSS 3.1CRITICAL 9.9
  • TI-2019-08259 Underflow in PHP-FPM can lead to RCE KEVCVSS 3.1CRITICAL 9.8
  • TI-2019-05363 Code injection in Elastic Kibana KEVCVSS 3.1CRITICAL 10.0
  • TI-2019-03949 Out-of-bounds write in ESXi and Horizon DaaS KEVCVSS 3.1CRITICAL 9.8
  • TI-2018-16080 A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153… KEVCVSS 3.1CRITICAL 9.8
See all 7413 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences