CVE-2026-104038

Sssd: sssd: denial of service via missing sid extension in certificate mapping

Published Oct 6, 2026 CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed

Description

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.

Analysis

Technical impact

A flaw in SSSD allows a remote attacker to cause a denial of service by submitting a certificate that lacks the required Microsoft Security Identifier (SID) extension. In configurations that employ SID‑based certificate mapping rules, the service attempts to access the missing extension before verification, leading to a process crash during authentication or lookup. The vulnerability is categorized as CWE‑476, a null or invalid pointer dereference.

Affected Systems

Red Hat Enterprise Linux versions 6 through 10 and Red Hat OpenShift Container Platform 4 are affected, as SSSD is deployed across these platforms. The issue specifically targets deployments that use "{sid}" or "{sid.rid}" expansion templates within LDAPU1 certificate mapping rules.

Risk and Exploitability

The CVSS score of 5.9 indicates medium severity, and the EPSS score is not available. The vulnerability is not listed in CISA KEV. Based on the description, the likely attack vector is remote authentication: an attacker sends a forged certificate lacking the SID extension over a trusted channel to a system running SSSD. This can force the service to crash, disrupting identity lookup and authentication until the service is restarted.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor	Product	Default status	Versions
Red Hat	Red Hat Enterprise Linux 10	affected	—
Red Hat	Red Hat Enterprise Linux 6	unknown	—
Red Hat	Red Hat Enterprise Linux 7	affected	—
Red Hat	Red Hat Enterprise Linux 8	affected	—
Red Hat	Red Hat Enterprise Linux 9	affected	—
Red Hat	Red Hat OpenShift Container Platform 4	affected	—
Red Hat	Red Hat OpenShift Container Platform 4	affected	—
Red Hat	Red Hat OpenShift Container Platform 5	affected	—

No data.

Vendor Product Versions

Redhat

Enterprise Linux

Version	Status	Scheme	Platform
`—`	affected	—	—

Redhat

Openshift Container Platform

Version	Status	Scheme	Platform
`—`	affected	—	—

Sssd

Version	Status	Scheme	Platform
`—`	affected	—	—

Remediation

Vendor Workaround

A configuration-based workaround is available. Until a fix is shipped, avoid SSSD certificate mapping rules whose LDAPU1 maprule expands the {sid} or {sid.rid} templates (for example, 'maprule = LDAPU1:(objectsid={sid.rid})'). If SID-based mapping is required, reject certificates that lack the Microsoft SID extension (OID 1.3.6.1.4.1.311.25.2) before they reach the affected certificate mapping evaluation path, so SID-based rules fail cleanly instead of crashing the service.

OpenCVE Recommended Actions

Reconfigure SSSD certificate mapping rules to avoid using "{sid}" or "{sid.rid}" expansion templates within LDAPU1 mapping rules.
Ensure certificates that do not contain the Microsoft SID extension (OID 1.3.6.1.4.1.311.25.2) are rejected before the mapping evaluation, using alternative certificate attributes for matching.
Restart the SSSD service to apply the new configuration and restore functionality.

Generated by OpenCVE AI on October 6, 2026 at 01:21 UTC.

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.267% probability within 30 days)

Exploitation poc

Automatable no

Technical Impact partial

References

Link	Providers
https://access.redhat.com/security/cve/CVE-2026-104038
https://bugzilla.redhat.com/show_bug.cgi?id=2478980
https://nvd.nist.gov/vuln/detail/CVE-2026-104038
https://www.cve.org/CVERecord?id=CVE-2026-104038

History

Nov 5, 2026 4:00 PM First appearance in the feed. Affected versions updated. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Redhat rhel Els
CPEs	cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:6 cpe:/o:redhat:enterprise_linux:7 cpe:/o:redhat:enterprise_linux:8 cpe:/o:redhat:enterprise_linux:9	cpe:/a:redhat:enterprise_linux:10 cpe:/a:redhat:enterprise_linux:8 cpe:/a:redhat:enterprise_linux:9 cpe:/a:redhat:openshift:5 cpe:/o:redhat:rhel_els:6 cpe:/o:redhat:rhel_els:7
Vendors & Products		Redhat rhel Els

Oct 7, 2026 9:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Oct 6, 2026 9:15 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Redhat openshift Container Platform Sssd Sssd sssd
Vendors & Products		Redhat openshift Container Platform Sssd Sssd sssd

Oct 6, 2026 12:15 PM Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
References		https://nvd.nist.gov/vuln/detail/CVE-2026-104038 https://www.cve.org/CVERecord?id=CVE-2026-104038
Metrics	threat_severity `None`	threat_severity `Moderate`

Oct 6, 2026 12:45 AM Description updated. Title updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		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.
Title		Sssd: sssd: denial of service via missing sid extension in certificate mapping
First Time appeared		Redhat Redhat enterprise Linux Redhat openshift
Weaknesses		CWE-476
CPEs		cpe:/a:redhat:openshift:4 cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:6 cpe:/o:redhat:enterprise_linux:7 cpe:/o:redhat:enterprise_linux:8 cpe:/o:redhat:enterprise_linux:9
Vendors & Products		Redhat Redhat enterprise Linux Redhat openshift
References		https://access.redhat.com/security/cve/CVE-2026-104038 https://bugzilla.redhat.com/show_bug.cgi?id=2478980
Metrics		cvssV3_1 `{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}`