---
id: CVE-2025-9820
title: >-
  A flaw was found in the GnuTLS library, specifically in the
  gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization
summary: >-
  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-…
severity: medium
cvss: 4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-121
published: '2026-01-26'
updated: '2026-06-25'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-9820'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2026:13812'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:3477'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:4188'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:4655'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:4943'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:5585'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:5606'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:7329'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2026:7477'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2025-9820'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2392528'
    label: secalert@redhat.com
  - url: >-
      https://gitlab.com/gnutls/gnutls/-/commit/1d56f96f6ab5034d677136b9d50b5a75dff0faf5
    label: secalert@redhat.com
  - url: 'https://gitlab.com/gnutls/gnutls/-/issues/1732'
    label: secalert@redhat.com
  - url: 'https://www.gnutls.org/security-new.html#GNUTLS-SA-2025-11-18'
    label: secalert@redhat.com
  - url: 'http://www.openwall.com/lists/oss-security/2025/11/20/2'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-032379.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.00226
epssPercentile: 0.13543
ingestedAt: '2026-06-29T13:24:34.636Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.