CVE-2026-104039

Sssd: sssd: denial of service via stale connection state reuse in pam gssapi responder

Published Oct 6, 2026 CVSS 3.1 · 4.7 Medium EPSS < 1% KEV · Not listed
Description
A flaw was found in SSSD. A local user can cause a denial of service (DoS) by disrupting system authentication services. When handling Generic Security Services Application Programming Interface (GSSAPI) authentication in the Pluggable Authentication Module (PAM) responder, cached connection state is freed upon completion without clearing the reference pointer. An attacker can exploit this by sending an additional request over the same connection, causing the service to access invalid memory and unexpectedly terminate.

Analysis

AI-generated

Technical impact

A local user can trigger a denial of service by exploiting a flaw in the SSSD PAM GSSAPI responder – cached connection state is freed without clearing the reference pointer, causing the service to read invalid memory when a new request is received on the same stale connection. The resultant crash interrupts authentication services and can render the system unusable until the service is restarted. The weakness is identified as a form of resource exhaustion and improper memory handling.

Affected Systems

Affected products are Red Hat Enterprise Linux 10, 6, 7, 8, and 9, as well as Red Hat OpenShift Container Platform 4. All these systems run the SSSD service that provides authentication integration.

Risk and Exploitability

The CVSS score of 4.7 indicates a moderate severity rating; the EPSS score is not available, and the vulnerability is not listed in the CISA KEV catalog. The attack requires a local user to send a specially crafted request over an existing GSSAPI connection. If successful, it leads to an application crash and a temporary denial of authentication services, affecting availability. The exploit is constrained to local privilege and does not require network exposure, which limits its attack surface to compromised or root users within the host.

Remediation

Vendor Workaround

A workaround is available for this issue. PAM GSSAPI authentication can be disabled in the SSSD configuration: edit /etc/sssd/sssd.conf, and in the [pam] section remove or comment out the pam_gssapi_services option (or set it to an empty value), so that no service is permitted to use GSSAPI authentication through the PAM responder. Then restart the SSSD service (systemctl restart sssd) to apply the change. Note that disabling PAM GSSAPI authentication prevents clients from authenticating to the affected PAM services using Kerberos tickets, requiring them to use alternative authentication methods such as passwords. Restarting the SSSD service also briefly disrupts ongoing authentication requests. Restarting the PAM responder can restore service after a crash, but it does not remove the underlying flaw.


OpenCVE Recommended Actions

  • Apply the latest SSSD security updates from the Red Hat repository.
  • If a patch is not yet available, restrict GSSAPI usage in PAM by disabling the responder or limiting it to trusted network interfaces.
  • Continuously monitor authentication service logs for abnormal restarts and apply critical updates as soon as they become available.

Generated by OpenCVE AI on October 6, 2026 at 02:24 UTC.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Redhat rhel Els
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
cpe:/a:redhat:enterprise_linux:10
cpe:/a:redhat:enterprise_linux:8
cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:rhel_els:6
cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
Type Values Removed Values Added
CPEs cpe:/a:redhat:openshift:5
Type Values Removed Values Added
First Time appeared Fedoraproject
Fedoraproject sssd
CPEs cpe:2.3:a:fedoraproject:sssd:2.12.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
Vendors & Products Fedoraproject
Fedoraproject sssd
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Redhat openshift Container Platform
Sssd
Sssd sssd
Vendors & Products Redhat openshift Container Platform
Sssd
Sssd sssd
Type Values Removed Values Added
Description A flaw was found in SSSD. A local user can cause a denial of service (DoS) by disrupting system authentication services. When handling Generic Security Services Application Programming Interface (GSSAPI) authentication in the Pluggable Authentication Module (PAM) responder, cached connection state is freed upon completion without clearing the reference pointer. An attacker can exploit this by sending an additional request over the same connection, causing the service to access invalid memory and unexpectedly terminate.
Title Sssd: sssd: denial of service via stale connection state reuse in pam gssapi responder
First Time appeared Redhat
Redhat enterprise Linux
Redhat openshift
Weaknesses CWE-825
CPEs cpe:/a:redhat:openshift:4
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat openshift
References
Metrics cvssV3_1

{'score': 4.7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses
  • CWE-825

    Expired Pointer Dereference

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 5, 2026, 3:52 PM
Reserved
Oct 1, 2026, 5:23 PM
Status
Analyzed
Published
Oct 6, 2026, 2:17 AM
Modified
Nov 5, 2026, 4:17 PM
Severity
Moderate
Public date
Oct 6, 2026, 12:41 AM