Quick answers
- Is CVE-2026-56391 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-56391 being exploited in the wild.
- How severe is CVE-2026-56391?
- Informational severity, with a CVSS score of 4.6, published 24 July 2026.
- Which products and versions are affected?
- Gnu Coreutils 9.5 through 9.11.
- Is there a fix for CVE-2026-56391?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-56391 attacked?
- It is attacked with local access, in an operating system.
- Am I affected by CVE-2026-56391?
- Check whether you run Gnu Coreutils at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
An out-of-bounds read vulnerability exists in the 'uniq' utility of GNU coreutils within the find_field() function. The flaw is caused by the incorrect handling of multibyte characters when the -w (--check-chars) flag is active; the function fails to advance a pointer correctly while calculating character byte lengths, leading to an inflated length value. This value is subsequently passed to memcmp(), resulting in a read beyond the allocated buffer. An attacker can exploit this by providing crafted multibyte input, potentially causing a denial-of-service (crash) or disclosing adjacent heap memory. The issue is fixed in commit d64e35a8a4c0e4608321433e0d84d917e4e36371.
Affected products
- GNU coreutils 9.5 through 9.11
Timeline
- 2026-07-24: disclosed
- 2026-07-24: advisory