// For flags

CVE-2025-9820

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

Severity Score

4.0
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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.

Tim Scheckenbach discovered that GnuTLS incorrectly handled malicious certificates containing a large number of name constraints and subject alternative names. A remote attacker could possibly use this issue to cause GnuTLS to consume resources, resulting in a denial of service. Luigino Camastra discovered that GnuTLS incorrectly handled certain PKCS11 token labels. A remote attacker could use this issue to cause GnuTLS to crash, resulting in a denial of service, or possibly execute arbitrary code. The default compiler options for affected releases should reduce the vulnerability to a denial of service.

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low
Attack Vector
Local
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2025-09-02 CVE Reserved
  • 2025-11-20 CVE Published
  • 2026-03-24 CVE Updated
  • 2026-03-24 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-121: Stack-based Buffer Overflow
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
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Red Hat
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 Enterprise Linux
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Affected
Redhat
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 Openshift
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Affected
Canonical
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 Ubuntu Linux
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Centos
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 Centos
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Debian
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 Debian Linux
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Fedoraproject
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 Fedora
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Freebsd
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 Freebsd
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Opensuse
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 Leap
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Redhat
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 Enterprise Linux
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Redhat
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 Openshift
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Slackware
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 Slackware Linux
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Suse
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 Sle-module-basesystem
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Suse
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 Sle Hpc
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Suse
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 Sled
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Suse
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 Sles-ltss-extended-security
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Suse
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 Sles
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Suse
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 Sles Sap
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Affected