CVE-2025-9820

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.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Applying the upstream patch or vendor-supplied security update is the recommended resolution.