Vulnerability · Published Jul 24, 2026 · Assigned by CERT-PL
CVE-2026-56391Out‑of‑bounds Read in GNU coreutils
Medium 4.6
In plain English
A medium-severity out-of-bounds read in coreutils from GNU. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
GNU coreutils uniq is vulnerable to an out‑of‑bounds read due to incorrect handling of multibyte input when the -w (--check-chars) option is used. The find_field() function miscalculates the byte length of characters by repeatedly processing a fixed pointer instead of advancing through the input, resulting in an inflated length value. This incorrect length is later used in a memcmp operation, causing reads beyond the allocated buffer when processing crafted multibyte input. When running GNU coreutils uniq with attacker-provided arguments, this behavior leads to a crash and potential adjacent heap memory exposure. This issue has been fixed in the commit d64e35a8a4c0e4608321433e0d84d917e4e36371.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | coreutils | 9.5-8.el10_2.1 | ALSA-2026:67886 |
| AlmaLinux:10 | coreutils-common | 9.5-8.el10_2.1 | ALSA-2026:67886 |
| AlmaLinux:10 | coreutils-single | 9.5-8.el10_2.1 | ALSA-2026:67886 |
| Debian:12 | coreutils | no fix listed | DEBIAN-CVE-2026-56391 |
| Debian:13 | coreutils | no fix listed | DEBIAN-CVE-2026-56391 |
| Debian:14 | coreutils | no fix listed | DEBIAN-CVE-2026-56391 |
| Rocky Linux:10 | coreutils | 0:9.5-8.el10_2.1 | RLSA-2026:67886 |
| Ubuntu:22.04:LTS | coreutils | 8.32-4.1ubuntu1.4 | USN-8697-1 |
| Ubuntu:24.04:LTS | coreutils | 9.4-3ubuntu6.3 | USN-8697-1 |
| Ubuntu:26.04:LTS | coreutils | 9.7-3ubuntu2.1 | USN-8697-1 |
| Ubuntu:26.04:LTS | coreutils | 9.7-3ubuntu2.1 | UBUNTU-CVE-2026-56391 |
Affected products (as reported)
Weakness: CWE-125 · Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N