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No exploitation reportedFix available

CVE-2026-56391

Out‑of‑bounds Read in GNU coreutils

No exploitation reported by the sources we read.

  • Published2026-07-24
  • WeaknessCWE-125

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-07-2409:16CVE publishedNVD

Versions per branch

NVD
Gnu coreutils
BranchAffectedFixed in
9.x≥ 9.5, ≤ 9.11no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As CERT-PL, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • GNU coreutilsother versions: not affected
    Affected
    • ≥ 9.5, ≤ 9.11no fix statedcustom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-07-24

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • coreutilsUbuntu:26.04:LTSall versions · fixed in 9.7-3ubuntu2.1
  • coreutilsUbuntu:24.04:LTSall versions · fixed in 9.4-3ubuntu6.3
  • coreutilsUbuntu:22.04:LTSall versions · fixed in 8.32-4.1ubuntu1.4
  • coreutilsSUSE:Linux Micro 6.2all versions · fixed in 9.6-160000.3.1and 1 other package
  • coreutilsSUSE:Linux Enterprise Server for SAP applications 16.0all versions · fixed in 9.6-160000.3.1and 2 other packages
  • coreutilsSUSE:Linux Enterprise Server 16.0all versions · fixed in 9.6-160000.3.1and 2 other packages
  • coreutilsRocky Linux:10all versions · fixed in 0:9.5-8.el10_2.1
  • coreutilsRed Hat:hummingbird:1all versions · fixed in 0:9.11-5.1.hum1and 2 other packages

9 more package ranges on OSV.dev

Vendor advisories

  • CVE-2026-56391 Red Hat Product Security24 products fixed · 14 known affected

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

    coreutils as a component of Red Hat Enterprise Linux 6 · coreutils-libs as a component of Red Hat Enterprise Linux 6 · coreutils.src as a component of Red Hat Enterprise Linux 6 · +11 more

  • RHSA-2026:67886 Red Hat Product Security21 products fixed

    Red Hat Security Advisory: coreutils security update

  • RHSA-2026:46515 Red Hat Product Security7 products fixed

    Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2026:67886 · 21 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  2. Vendor fix Red Hat Product Security RHSA-2026:46515 · 7 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
  3. Workaround from the vendor Red Hat Product Security RHSA-2026:67886 · 25 productsMitigation 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.
  4. No fix available, says the vendor Red Hat Product Security CVE-2026-56391 · 10 productsFix deferred
  5. No fix planned, says the vendor Red Hat Product Security CVE-2026-56391 · 4 productsOut of support scope

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H
CVSS 4.0 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/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
Published
2026-07-24
Last Modified
2026-10-24
NVD status
Analyzed
GitHub Advisory
GHSA-7xvj-m9x7-qgxq

Frequently asked questions

What is CVE-2026-56391?

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.

Is CVE-2026-56391 actively exploited?

Active exploitation of CVE-2026-56391 has not been confirmed. Its EPSS score was 0.1% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-56391?

CVE-2026-56391 has a CVSS v3 base score of 6.1 (MEDIUM severity), with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H.

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