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GNU patch EUVDEUVD-2026-42556

| CVE-2026-56288 MEDIUM
NULL Pointer Dereference (CWE-476)
2026-07-09 CERT-PL GHSA-m3j2-9m66-r96h
Denial Of Service Null Pointer Dereference Patch
4.6
CVSS 4.0 · Vendor: CERT-PL
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Severity by source

Vendor (CERT-PL) PRIMARY
4.6 MEDIUM
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
3.3 LOW

Local attack requiring active user invocation of patch against a malicious file (UI:R); no privileges needed; impact is solely a process crash with no confidentiality or integrity exposure (A:L only).

3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
4.0 AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (CERT-PL).

CVSS VectorVendor: CERT-PL

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
A
Scope
X

Lifecycle Timeline

1
Analysis Generated
Jul 09, 2026 - 12:09 vuln.today

DescriptionCVE.org

GNU patch is vulnerable to a NULL pointer dereference when processing a specially crafted unified-diff patch file. Improper handling of consecutive end-of-file newline markers can corrupt internal hunk (single block of changes in diff) data structures, causing the application to pass a NULL pointer to fwrite() during patch processing. An attacker can trigger this condition with a malicious patch file, causing the utility to crash and resulting in a denial of service.

This issue has been fixed in the commit e6d6a4e021660679d7fc9150f981d4920f722313

AnalysisAI

GNU patch crashes with a NULL pointer dereference when a user applies a specially crafted unified-diff file, resulting in denial of service. Improper handling of consecutive end-of-file newline markers corrupts internal hunk data structures, causing a NULL pointer to be passed to fwrite() during processing. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Craft unified-diff with malformed EOF newline markers
Delivery
Deliver malicious file to target user or pipeline
Exploit
User invokes GNU patch against crafted file
Execution
Consecutive EOF markers corrupt hunk data structures
Persist
NULL pointer passed to fwrite()
Impact
patch process crashes (DoS)
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Vulnerability AssessmentAI

Exploitation The victim must actively invoke the GNU patch utility and supply the crafted unified-diff file as input - confirmed by CVSS UI:A (active user interaction required). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 score of 4.6 with vector AV:L/AC:L/AT:N/PR:N/UI:A/VA:L accurately reflects the constrained threat model: exploitation is local, requires user interaction, and yields only a limited availability impact (crash of the patch process, not system-wide disruption). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker crafts a unified-diff file containing specially structured consecutive end-of-file newline markers and delivers it to a developer or sysadmin - for example, as a malicious patch submission to an open-source project or via a compromised repository. When the victim runs the patch command against this file, the corrupted hunk data structure causes a NULL pointer dereference in fwrite(), crashing the utility and potentially disrupting automated patch-application workflows.
Remediation The upstream fix is available as commit e6d6a4e021660679d7fc9150f981d4920f722313 in the GNU patch Savannah repository (https://cgit.git.savannah.gnu.org/cgit/patch.git/commit/?id=e6d6a4e021660679d7fc9150f981d4920f722313); a formal tagged release version has not been independently confirmed, so this is an upstream commit fix pending a versioned release. … Detailed patch versions, workarounds, and compensating controls in full report.
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EUVD-2026-42556 vulnerability details – vuln.today
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