Medium [CVE-2025-9820] Gnutls: stack-based buffer overflow in gnutls_pkcs11_token_init function

A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer.

This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.

The Red Hat Product Security team has assessed the severity of this vulnerability as Low, since exploitation requires local access or a malicious PKCS#11 token.

While the impact is limited to denial of service or potential code execution in constrained scenarios, the vulnerability stems from a lack of proper bounds checking during token label handling in GnuTLS. Users should treat this as a security concern in environments where untrusted tokens may be introduced.

Weakness: CWE-121.

Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; RHEL-8 based Middleware Containers; Red Hat Ceph Storage 8; Red Hat Discovery 2; Red Hat Hardened Images; Red Hat Insights proxy 1.5; Red Hat Update Infrastructure 5; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat OpenShift Container Platform 4.