CVE-2026-104039: Sssd: sssd: denial of service via stale connection state reuse in pam gssapi responder
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.1%
EPSS score, percentile 0.9 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 4.7 Medium
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Workaround (from the CVE record)
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.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
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Versions not listed are: unknown.
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Versions not listed are: affected.
Source: CVE List, as of . About the data.
About this vulnerability
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 sen…
Summary: CVE record, as of .
- CISA has not added CVE-2026-104039 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 6 Oct 2026.
- The CVE record carries a CVSS v3.1 base score of 4.7 (Medium), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.1% (percentile 0.9), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact partial.
- The credits in the CVE record name AISLE as finder.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
Sssd: sssd: denial of service via stale connection state reuse in pam gssapi responder
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.
Source: CVE List, as of . About the data.
Weakness
CWE-825
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
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References
2
Known exploited Red Hat vulnerabilities
- CVE-2015-3246: Red Hat Libuser Race Condition Vulnerability
- CVE-2015-5287: Red Hat Automatic Bug Reporting Tool Privilege Escalation Vulnerability
- CVE-2018-14667: Red Hat JBoss RichFaces Framework Expression Language Injection Vulnerability
- CVE-2021-3560: Red Hat Polkit Incorrect Authorization Vulnerability
- CVE-2021-4034: Red Hat Polkit Out-of-Bounds Read and Write Vulnerability