Is CVE-2026-127099 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-127099 being exploited in the wild.

How severe is CVE-2026-127099?

Medium severity, with a CVSS score of 5.9, published 12 November 2026.

Is there a fix for CVE-2026-127099?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-127099 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-127099?

Check whether you run Red Hat SSSD. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-127099: SSSD stack buffer overflow in X.509 RSA certificate conversion

CVE-2026-127099 · Severity: medium · CVSS 5.9 · Published 2026-11-12

SSSD is a system daemon that manages user authentication and authorization across Linux systems. The vulnerability allows an attacker with the ability to supply a specially crafted certificate to trigger a denial-of-service condition or corrupt SSH authentication memory. Exploitation requires the attacker to pass the system's certificate validation checks and have low-level access to certificate attributes.

Technologies: Red Hat SSSD. Vendors: Red Hat.

Quick answers

Is CVE-2026-127099 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-127099 being exploited in the wild.
How severe is CVE-2026-127099?: Medium severity, with a CVSS score of 5.9, published 12 November 2026.
Which products and versions are affected?: Red Hat SSSD.
Is there a fix for CVE-2026-127099?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-127099 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-127099?: Check whether you run Red Hat SSSD. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A stack buffer overflow exists in SSSD's conversion of X.509 certificate RSA public keys to SSH keys due to missing size validation before copying RSA components into fixed-size buffers. The vulnerability is reachable via network through certificate-based SSH key lookup; exploitation requires an attacker-controlled certificate passing configured validation checks and low-privileged certificate attribute write access. Successful exploitation causes SSH responder denial of service and memory corruption, though arbitrary code execution has not been demonstrated.

Affected products

Red Hat SSSD

Timeline

2026-11-12: disclosed

References

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