# CVE-2026-127099: Sssd: sssd: stack buffer overflow during rsa certificate-to-ssh key conversion

Status: published. Published: 2026-11-12. Updated: 2026-11-12.

A flaw was found in SSSD's conversion of X.509 certificate RSA public keys to SSH keys. Missing size checks before copying RSA components into fixed-size stack buffers can cause a stack buffer overflow. An attacker able to supply a certificate with oversized RSA components that passes the configured certificate checks can cause denial of service and corrupt SSH responder memory.

## Remediation

- workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. (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:L/UI:N/S:U/C:N/I:L/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: Not available

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

- Weaknesses: CWE-121

## Exploit evidence

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

## References

- https://access.redhat.com/security/cve/CVE-2026-127099 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2572590 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-127099; retrieved 2026-11-12; source updated 2026-11-12

Revision: 94e2749258c69ffd618c9146e196c2f1bc478a5999e931efd9d76e4d13ec2bef

Canonical: https://y2.dev/cve/CVE-2026-127099

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