CVE-2026-56289

Description

GNU patch is vulnerable to a denial of service (DoS) due to improper validation of hunk (single block of changes in diff) line offsets in unified-diff input. A specially crafted patch can specify an extremely large line number, causing the application to enter an effectively infinite processing loop while attempting to locate the requested position. This results in excessive CPU consumption and prevents the process from completing. An attacker can trigger this behavior by supplying a malicious patch file, causing the utility to become unresponsive and require manual termination. This issue has been fixed in the commit faba04ef4f2b410257f76c1b9dc85e350929c4b9

Read the notes from the security team

Why is this CVE low priority?

Only a DoS in a command line tool

Learn more about Ubuntu priority

Status

Show unmaintained releases

Package	Ubuntu Release	Status
patch	26.04 LTS resolute	Needs evaluation
	25.10 questing	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
	14.04 LTS trusty	Needs evaluation

Notes

mdeslaur

This is a DoS in a command line tool with little security impact, marking priority as low

Patch details

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

Package	Patch details
patch	Upstream: ?id=fab

Severity score breakdown

CVSS version:

Base score 4.6 · Medium

Base metrics

Parameter	Value
Attack vector	Local
Attack complexity	Low
Attack requirements	None
Privileges required	None
User interaction	Active
Vulnerable system - Confidentiality impact	None
Vulnerable system - Integrity impact	None
Vulnerable system - Availability impact	Low
Subsequent system - Confidentiality impact	None
Subsequent system - Integrity impact	None
Subsequent system - Availability impact	Low

Scores

Parameter	Value
Base score	4.6 · Medium
Base + Threat score	-
Base + Environmental score	-
Base + Threat + Environmental score	-

Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

Base score 5.5 · Medium

Base metrics

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

Scores

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

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

CVE-2026-56289

Cvss 3 Severity Score