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Fencer Vulns
medium 6.1

CVE-2026-56391 json

Out‑of‑bounds Read in GNU coreutils

published 2026-07-24 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-48524 , GHSA-7xvj-m9x7-qgxq , JLSEC-2026-1195

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • coreutils Ubuntu 26.04 LTS 9.7-3ubuntu2.1

ubuntu advisories UBUNTU-CVE-2026-56391

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • coreutils RHEL 10.2 9.5-8.el10_2.1
  • coreutils-single RHEL 10.2 9.5-8.el10_2.1
  • coreutils hummingbird 1 9.11-5.1.hum1
  • coreutils-common hummingbird 1 9.11-5.1.hum1
  • coreutils-single hummingbird 1 9.11-5.1.hum1

red hat advisories RHSA-2026:67886RHSA-2026:46515

  • coreutils SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 9.6-160000.3.1
  • coreutils-single SLES for SAP applications 16.0, SLES 16.0 9.6-160000.3.1
  • coreutils-systemd SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 9.6-160000.3.1

suse advisories SUSE-SU-2026:24268-1SUSE-SU-2026:24406-1

  • coreutils openSUSE Leap 16.0 9.6-160000.3.1
  • coreutils-single openSUSE Leap 16.0 9.6-160000.3.1
  • coreutils-systemd openSUSE Leap 16.0 9.6-160000.3.1
  • coreutils-testsuite openSUSE Leap 16.0 9.6-160000.3.1
  • coreutils openSUSE Tumbleweed 9.11-5.1

opensuse advisories openSUSE-SU-2026:22147-1openSUSE-SU-2026:11764-1

  • coreutils AlmaLinux 10 9.5-8.el10_2.1
  • coreutils-common AlmaLinux 10 9.5-8.el10_2.1
  • coreutils-single AlmaLinux 10 9.5-8.el10_2.1

almalinux advisories ALSA-2026:67886

  • coreutils Rocky Linux 10 9.5-8.el10_2.1

rocky linux advisories RLSA-2026:67886

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-56391 updated cvss 6.1

coreutils: GNU coreutils uniq: Denial of Service and information disclosure via out-of-bounds read with multibyte input

  • Red Hat Enterprise Linux 6 coreutils, coreutils-libs Red Hat Enterprise Linux 7 coreutils
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 coreutils, coreutils-common, coreutils-single Red Hat Enterprise Linux 9 coreutils, coreutils-common, coreutils-single Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-mod-arch-mlflow-rhel9, +6 more
    under investigation
  • Red Hat Enterprise Linux BaseOS (v. 10) coreutils 9.5-8.el10_2.1, coreutils-single 9.5-8.el10_2.1
    fixed: vendor fix RHSA-2026:67886
  • Red Hat Hardened Images coreutils 9.11-5.1.hum1, coreutils-common 9.11-5.1.hum1, coreutils-single 9.11-5.1.hum1
    fixed: vendor fix RHSA-2026:46515
  • Red Hat Enterprise Linux BaseOS (v. 10) coreutils-common 9.5-8.el10_2.1 Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-kube-rbac-proxy-rhel9, rhoai/odh-maas-controller-rhel9, rhoai/odh-mlflow-operator-rhel9, rhoai/odh-model-controller-rhel9, rhoai/odh-ogx-k8s-operator-rhel9, +14 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 4.6 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
CNA 4.0 4.6 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/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
NVD 3.1 6.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H

Affected packages

ecosystem package affected fixed in
julia coreutils_jll
>=9.5.0+0
 no fix listed

Affected products

  • GNU coreutils

Classification

Weakness

References

Sources

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