CVE-2025-9820

Publication date 26 January 2026

Last updated 28 January 2026

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Why is this CVE low priority?

GnuTLS developers have rated this to be low severity

Learn more about Ubuntu priority

Status

Show unmaintained releases

Package	Ubuntu Release	Status
gnutls28	25.10 questing	Needs evaluation
	25.04 plucky	Ignored end of life, was needs-triage
	24.04 LTS noble	Needs evaluation
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation

Notes

mdeslaur

Ubuntu builds are built with stack protector, mitigating this issue

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
gnutls28	Upstream: 1d56f96

Severity score breakdown

Parameter	Value
Base score	4.0 · Medium
Attack vector	Local
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	Low
Vector	CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L