CVE-2026-18374

Publication date 27 August 2026

Last updated 3 September 2026

Ubuntu priority

Cvss 3 Severity Score

Description

Passing an effectively empty string to the `,ccs=` syntax extension of the mode argument in the `fopen` function in the GNU C Library version 2.45 or earlier may result in a heap buffer overflow when the mode string input to the function is attacker controlled. This usage pattern is not seen in applications in common GNU/Linux distributions and applications that process user-supplied values for `ccs` should not pass them through without validation.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
glibc	26.04 LTS resolute	Vulnerable, fix deferred
	24.04 LTS noble	Vulnerable, fix deferred
	22.04 LTS jammy	Vulnerable, fix deferred
	20.04 LTS focal	Vulnerable, fix deferred
	18.04 LTS bionic	Vulnerable, fix deferred
	16.04 LTS xenial	Vulnerable, fix deferred
eglibc	26.04 LTS resolute	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	14.04 LTS trusty	Vulnerable, fix deferred

Notes

mdeslaur

As of 2026-09-03, there is no fix from glibc developers for this issue.

Severity score breakdown

CVSS version: CVSS v3.0

Base score 4.9 · Medium

Base metrics

Parameter	Value
Attack vector	Local
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	Low
Integrity impact	Low
Availability impact	Low

Scores

Parameter	Value
Base score	4.9 · Medium
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L