CVE-2026-56288
Description
A flaw was found in GNU patch. An attacker can exploit this by providing a specially crafted patch file, which leads to a NULL pointer dereference. This improper handling of end-of-file markers can corrupt internal data structures, causing the utility to crash. This results in a denial of service (DoS) for the affected system.
Statement
A denial-of-service vulnerability of moderate severity was found in GNU patch, which is shipped in Red Hat Hardened Images. When patch processes a specially crafted unified-diff patch file, improper handling of consecutive end-of-file newline markers can corrupt internal hunk data structures, causing a NULL pointer to be passed to fwrite() during patch processing and the utility to crash. An attacker who supplies a malicious patch file that a user then applies can trigger this crash, disrupting patch processing on the affected system; the flaw has no impact on confidentiality or integrity, and exploitation requires local processing of an attacker-controlled patch file with user interaction. Red Hat Product Security rated this flaw Moderate impact (CVSS 3.1 score 5.0), slightly lower than the NIST score of 5.5 because applying the crafted patch file requires user interaction. The Red Hat Hardened Images product is affected by this flaw, and a fix is being pursued through the responsible upstream and product channels.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | Required | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
