CVE-2026-104039
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.
Fixes and workarounds
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.
Source: CNA: redhatAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| Red Hat Enterprise Linux 10 Red Hat sssd
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 6 Red Hat sssd
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: unknown |
CNA: redhat |
| Red Hat Enterprise Linux 7 Red Hat sssd
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 8 Red Hat sssd
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat Enterprise Linux 9 Red Hat sssd
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift Container Platform 4 Red Hat openshift/ose-rhel-coreos-8
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift Container Platform 4 Red Hat openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
| Red Hat OpenShift Container Platform 5 Red Hat openshift/ose-rhel-coreos-9
https://access.redhat.com/downloads/content/package-browser/ |
Range not reported
Other versions: affected |
CNA: redhat |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
NVD applicability configurations (1)
These expressions retain AND/OR operators, negation, and required environmental products. A listed product is not sufficient to establish exposure when additional conditions apply.
[
{
"negate": false,
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:fedoraproject:sssd:2.12.0:*:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "OR"
}
]CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 4.7 medium |
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H | CNA: redhat |
| 3.1 / 5.5 medium |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | NVD: [email protected] |
| 3.1 / 4.7 medium |
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H | NVD: [email protected] |
Exploit evidence
References
- https://access.redhat.com/security/cve/CVE-2026-104039CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2478956CNA: redhat · issue-tracking, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-104039[email protected] · Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2478956[email protected] · Exploit, Issue Tracking, Mitigation, Vendor Advisory
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