Heap-based Buffer Overflow in GNU coreutils

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-56392
StatePUBLISHED
AssignerCERT-PL
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-24 09:16:25 UTC
Updated2026-07-30 16:28:33 UTC
DescriptionGNU coreutils unexpand is vulnerable to a heap-based buffer overflow due to an integer overflow during buffer allocation when processing large tab stop (-t) values. The multiplication used to calculate the allocation size can wrap around, resulting in an undersized buffer. When processing crafted input, subsequent writes exceed the allocated memory, leading to an out‑of‑bounds heap write. When running GNU coreutils unexpand with attacker-provided large tab stop (-t) arguments, this behavior leads to a crash and potentially achieve a heap write primitive depending on memory layout. This issue has been fixed in the commit b60a159fdc5bfcf9988d3a4cb6f53abe8ad5d35d

Risk And Classification

Primary CVSS: v4.0 1.8 LOW from [email protected]

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/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

EPSS: 0.001490000 probability, percentile 0.045660000 (date 2026-08-03)

Problem Types: CWE-122 | CWE-122 CWE-122 Heap-based Buffer Overflow

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary1.8LOWCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS1.8LOWCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Active
Confidentiality
None
Integrity
Low
Availability
Low
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA GNU Coreutils affected 9.11 custom Not specified

References

ReferenceSourceLinkTags
git.savannah.gnu.org/cgit/coreutils.git [email protected] git.savannah.gnu.org
git.savannah.gnu.org/cgit/coreutils.git/commit [email protected] git.savannah.gnu.org
cert.pl/en/posts/2026/07/CVE-2026-56391 [email protected] cert.pl
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Michał Majchrowicz (AFINE Team) (en)

CNA: Marcin Wyczechowski (AFINE Team) (en)

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