CVE-2026-5745

Publication date 7 April 2026

Last updated 6 August 2026

Ubuntu priority

Cvss 3 Severity Score

Description

A flaw was found in libarchive. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_text_nl() function. When processing a malformed ACL string (such as a bare "d" or "default" tag without subsequent fields), the function fails to perform adequate validation before advancing the pointer. An attacker can exploit this by providing a maliciously crafted archive, causing an application utilizing the libarchive API (such as bsdtar) to crash, resulting in a Denial of Service (DoS).

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
libarchive	26.04 LTS resolute	Fixed 3.8.5-1ubuntu2.2
	25.10 questing	Ignored end of life, was needed
	24.04 LTS noble	Fixed 3.7.2-2ubuntu0.8
	22.04 LTS jammy	Fixed 3.6.0-1ubuntu1.8
	20.04 LTS focal	Fixed 3.4.0-2ubuntu1.5+esm3
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

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Notes

mdeslaur

There is a commit to fix this issue, but the CVE will likely be rejected by libarchive developers. Per libarchive developer "The root cause remains a UBSAN violation, not a NULL pointer dereference"

Patch details

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

Package	Patch details
libarchive	Upstream: 5f70255

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.5 · Medium

Base metrics

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

Scores

Parameter	Value
Base score	5.5 · Medium
Exploitability score	-
Impact score	-