OESA-2026-4594: sssd security update
Provides a set of daemons to manage access to remote directories and authentication mechanisms. It provides an NSS and PAM interface toward the system and a pluggable back end system to connect to multiple different account sources. It is also the basis to provide client auditing and policy services for projects like FreeIPA. Security Fix(es):
A flaw was found in SSSD's NFS idmap plugin. When retrieving cached user or group names, the plugin detects if an entry exceeds the destination buffer size but fails to abort before copying data. A local attacker can trigger this vulnerability by requesting identity lookups that resolve to oversized cached entries, resulting in an out-of-bounds write. This flaw primarily leads to a Denial of Service (DoS) by crashing the identity mapping service, and may also corrupt adjacent process memory.(CVE-2026-104036)
A flaw was found in sssd. A remote attacker can cause a denial of service (DoS) by submitting a certificate that lacks an expected Security Identifier (SID) extension. In deployments configured with SID-based certificate mapping rules, the service fails to verify the presence of the extension before processing it, causing the process to crash during authentication or lookup operations.(CVE-2026-104038)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
openeuler/sssdto a version that resolves this vulnerability.Fixed in 2.9.4-30.oe2403sp4
Event History
Frequently Asked Questions
Which systems are exposed to the NFS identity-mapping issue?
Systems using SSSD's NFS idmap plugin are exposed when identity lookups can resolve to oversized cached user or group name entries. Exploitation requires local access to request those lookups.
What is the expected impact of exploiting the NFS idmap flaw?
The out-of-bounds write primarily causes denial of service by crashing the identity-mapping service. It may also corrupt adjacent process memory.
When does the certificate-related denial of service apply?
It applies to deployments configured with SID-based certificate mapping rules. A remote attacker can submit a certificate without the expected SID extension, causing the service to process an absent extension and leading to denial of service.