# CVE-2026-104038: Sssd: sssd: denial of service via missing sid extension in certificate mapping

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

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.

## Remediation

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

- CVSS 3.1: 5.9 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 0.27% as of 2026-11-05; percentile 18.94%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-476

## Exploit evidence

- exploit: https://bugzilla.redhat.com/show_bug.cgi?id=2478980 (ADP: CISA-ADP)

## References

- https://access.redhat.com/security/cve/CVE-2026-104038 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2478980 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2478980 (ADP: CISA-ADP; exploit)

- https://access.redhat.com/security/cve/CVE-2026-104038 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2478980 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2478980 (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-104038; retrieved 2026-11-05; source updated 2026-11-05

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104038; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-104038; retrieved 2026-11-05; source updated Not reported

Revision: 8ad2b144152d474100a5a0fe883dbb6df73c7dd71d0b8ca66657d0c718c89399

Canonical: https://y2.dev/cve/CVE-2026-104038

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.