# CVE-2026-104036: Sssd: sssd: denial of service via out-of-bounds write in nfs idmap plugin

Status: published. Published: 2026-10-06. Updated: 2026-11-05.

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.

## Remediation

- 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: 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

## Severity and prioritization

- CVSS 3.1: 5.8 (medium); CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H; source: CNA: redhat

- CVSS 3.1: 5.8 (medium); CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 0.09% as of 2026-11-05; percentile 0.38%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/security/cve/CVE-2026-104036 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2479057 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-104036 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2479057 (secalert@redhat.com)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-104036; retrieved 2026-11-05; source updated 2026-11-05

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104036; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-104036; retrieved 2026-11-05; source updated Not reported

Revision: 7cc0cc2361de1ed50fea86414a857f913567fe5f89d00553b72019e159e45937

Canonical: https://y2.dev/cve/CVE-2026-104036

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