# CVE-2026-104039: Sssd: sssd: denial of service via stale connection state reuse in pam gssapi responder Status: published. Published: 2026-10-06. Updated: 2026-11-05. 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. ## Remediation - 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: redhat) ## Affected products and versions - Red Hat / Red Hat Enterprise Linux 10 (sssd): Version range not reported. Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 6 (sssd): Version range not reported. Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 7 (sssd): Version range not reported. Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 8 (sssd): Version range not reported. Source: CNA: redhat - Red Hat / Red Hat Enterprise Linux 9 (sssd): Version range not reported. Source: CNA: redhat - Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat - Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat - Red Hat / Red Hat OpenShift Container Platform 5 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat ## NVD configuration conditions Affected CPE matches depend on the following AND/OR and negation conditions: ```json [ { "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" } ] ``` ## Severity and prioritization - CVSS 3.1: 4.7 (medium); CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H; source: CNA: redhat - CVSS 3.1: 5.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: NVD: nvd@nist.gov - CVSS 3.1: 4.7 (medium); CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H; source: NVD: secalert@redhat.com - CISA KEV: No listing in collected sources - EPSS: 0.13% as of 2026-11-05; percentile 2.73% - SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP - Weaknesses: CWE-825 ## Exploit evidence - exploit: https://bugzilla.redhat.com/show_bug.cgi?id=2478956 (secalert@redhat.com) ## References - https://access.redhat.com/security/cve/CVE-2026-104039 (CNA: redhat; vdb-entry, x_refsource_REDHAT) - https://bugzilla.redhat.com/show_bug.cgi?id=2478956 (CNA: redhat; issue-tracking, x_refsource_REDHAT) - https://access.redhat.com/security/cve/CVE-2026-104039 (secalert@redhat.com; Vendor Advisory) - https://bugzilla.redhat.com/show_bug.cgi?id=2478956 (secalert@redhat.com; Exploit, Issue Tracking, Mitigation, Vendor Advisory) ## Provenance - CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-104039; retrieved 2026-11-05; source updated 2026-11-05 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104039; retrieved 2026-11-05; source updated 2026-11-05 - FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-104039; retrieved 2026-11-05; source updated Not reported Revision: ebb32645866808e074c58e8978307f2ca23f759a9c3378060f034992a84ed30c Canonical: https://y2.dev/cve/CVE-2026-104039 ## Agent and API access Public CVE pages, Markdown, and JSON are free to read without an account or API key. - Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end. - WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers. - Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}. - Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer . Setup: https://y2.dev/docs/api/create-key. - x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402. - OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json. Collected public records only. Check source status for coverage and freshness.