GNU patch fixes two DoS vulnerabilities
CERT Polska coordinated disclosure of two GNU patch vulnerabilities that let malicious diff files crash or hang the utility.
Sourcecert.pl — open the original
What to check
- Applies to
- The 2 CVEs named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- No exploitation in the wild and no public exploit is recorded for the CVEs named.
CERT Polska disclosed two vulnerabilities in GNU patch, a widely used utility for applying diff files, reported by AFINE Team researchers Michał Majchrowicz and Marcin Wyczechowski. CVE-2026-56288 is a NULL pointer dereference caused by improper handling of consecutive end-of-file newline markers, which corrupts internal hunk data structures and leads to a crash when a NULL pointer is passed to fwrite(). CVE-2026-56289 is a denial-of-service issue stemming from improper validation of hunk line offsets, allowing a crafted patch file to specify an extremely large line number and force the application into an effectively infinite loop, consuming excessive CPU and hanging the process.
Both issues require a victim to process a specially crafted unified-diff patch file, making exploitation dependent on social engineering or automated patch-processing pipelines that ingest untrusted diffs. Both vulnerabilities are fixed upstream via dedicated commits. No evidence of active exploitation is mentioned; this is a coordinated disclosure of denial-of-service bugs rather than remote code execution.
Mentioned in this report
Source reporting: https://cert.pl/en/posts/2026/07/CVE-2026-56288
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