CVE-2026-56392
GNU 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
CSIRTS triage
- What
- A heap-based buffer overflow vulnerability exists in GNU coreutils.
- Who is affected
- Users of GNU coreutils.
- Urgency
- Remediation is critical due to the potential for exploitation, though no active exploits are reported.
- Action
- Update to the latest version of GNU coreutils that addresses this vulnerability.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.15% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 5% of all EPSS-scored CVEs.
Advisory coverage (2)
- unknownCVE-2026-56392: GNU coreutils unexpand is vulnerable to a heap-based buffer overflow due to an integer overflo…nvd · 2026-07-24
- unknownCVE-2026-56392: Heap-based Buffer Overflow in GNU coreutilsmsrc · 2026-07-14
External references
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