CVE-2026-56289: GNU patch is vulnerable to a denial of service (DoS) due to improper validation of hunk (single block of chang

Q: How do I fix CVE-2026-56289?

patch: upgrade to newer than 2.8.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-56289 being exploited?

CVE-2026-56289 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-56289 affect?

CVE-2026-56289 affects patch. Severity is medium (CVSS 5.5). 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

Q: How urgent is CVE-2026-56289?

Priority 20/100. No elevated risk signals yet.

Routine

MEDIUM 5.5UPGRADE

CVE-2026-56289 is a medium-severity flaw (CVSS 5.5) affecting patch. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 ca

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.1% (top 98%)
CISA exploited list	No
Weakness	CWE-835
Published	2026-07-09
Last modified	2026-10-25

Publisher (CNA): CERT.PL · Vendor: gnu

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-09 11:16 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

gnu patch UPGRADE

Affected: <= 2.8.0

Fixed in: newer than 2.8.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy patch || rpm -q patch || patch --version

2. UPGRADE to newer than 2.8.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade patch

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade patch

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Advisories and coverage

Official advisories

CERT Polska: Vulnerabilities in GNU patch software 2026-07-09

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-56289?

patch: upgrade to newer than 2.8.0. Exact commands for each OS are on this page.

Is CVE-2026-56289 being exploited?

CVE-2026-56289 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-56289 affect?

CVE-2026-56289 affects patch. Severity is medium (CVSS 5.5). 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

How urgent is CVE-2026-56289?

Priority 20/100. No elevated risk signals yet.

Related CVEs

CVE-2026-56288 MEDIUM 5.5 UPGRADE GNU patch is vulnerable to a NULL pointer dereference when processing a specially crafted unified-diff patch f

References

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