CVE-2026-127099: Stack Overflow (CVSS 5.9)

Description

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.

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CVSS v3.1 Score

5.9

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H

Weakness Type (CWE)

CWE-121 CWE-121

References

Other References

https://access.redhat.com/security/cve/CVE-2026-127099 https://bugzilla.redhat.com/show_bug.cgi?id=2572590

Frequently Asked Questions

What is CVE-2026-127099? +

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. It has a CVSS v3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2026-127099? +

CVE-2026-127099 has a CVSS v3.1 score of 5.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-127099? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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