CVE-2026-104039 Red Hat CVE debrief

Who should care

System administrators and security teams responsible for managing SSSD configurations and GSSAPI authentication in their environments should assess exposure and verify configurations to prevent potential DoS attacks.

Why it matters

CVE-2026-104039 is a vulnerability in SSSD that can lead to denial of service (DoS) attacks through exploitation of GSSAPI authentication in the PAM responder. Defenders should prioritize verifying and updating SSSD configurations to prevent potential DoS attacks, especially in systems handling GSSAPI authentication.

• Potential disruption of system authentication services
• Denial of service (DoS) attacks through exploitation of the vulnerability
• Need for verification and update of SSSD configurations
• Potential impact on system availability and security

Technical summary

A flaw in SSSD allows a local user to cause a denial of service (DoS) by disrupting system authentication services. When handling GSSAPI authentication in the 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.

Defensive priority

Defenders should prioritize verifying and updating SSSD configurations, especially in systems handling GSSAPI authentication, to prevent potential DoS attacks.

Recommended defensive actions

• Verify and update SSSD configurations to prevent potential DoS attacks
• Review system authentication services for GSSAPI authentication vulnerabilities
• Monitor for unusual activity in systems handling GSSAPI authentication
• Perform asset inventory of systems using GSSAPI authentication
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description and potential impact. However, specific versions affected and remediation steps are not provided. Defenders should verify SSSD configurations, review system authentication services for GSSAPI authentication vulnerabilities, and monitor for unusual activity in systems handling GSSAPI authentication. Evidence limits suggest focusing on known affected systems and verifying configurations to prevent potential DoS attacks.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.