CVE-2025-9820

Gnutls: stack-based buffer overflow in gnutls_pkcs11_token_init() function

MEDIUM
4
CVSS Score
Published: January 26, 2026 at 07:58 PM UTC
Updated: October 14, 2026 at 08:17 PM UTC
3 products affected across 2 vendorsEnterprise LinuxOpenShift Container PlatformSIMATIC CN 4100

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Severity
MEDIUM4
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions6
Vendor states this is fixed in 0:3.6.16-8.el8_10.5 (unaffected)
Vendor states this is fixed in 0:3.8.10-3.el10_1 (unaffected)
Vendor states this is fixed in 0:3.8.3-10.el9_7 (unaffected)
v < V5.0
Affected range stops below V5.0, so it looks safe — our inference, not a vendor statement

References (20)

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4MEDIUMredhat
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-121

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