CVE-2026-104036
Sssd: sssd: denial of service via out-of-bounds write in nfs idmap plugin
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.
Fixes and workarounds
Workaround
Disable the vulnerable memcache lookup path of the SSSD NFS idmap plugin: in the rpc.idmapd configuration, set `memcache = false` for the SSSD plugin (or switch the translation `Method` away from `sss`), and restart the rpc.idmapd service to apply the change. This makes uid/gid name lookups bypass the vulnerable get_user_from_mc() and get_group_from_mc() code paths. Note that with memcache disabled, lookups are served through the SSSD responder instead of the in-memory cache, which may add lookup latency on systems with heavy NFS identity resolution traffic. No released package fix is currently established for this issue, so this configuration change is the recommended interim workaround until a fixed build is available.
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.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 5.8 medium |
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H | CNA: redhat |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://access.redhat.com/security/cve/CVE-2026-104036CNA: redhat · vdb-entry, x_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2479057CNA: redhat · issue-tracking, x_refsource_REDHAT
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