CVE-2026-56392 Heap-based Buffer Overflow in GNU coreutils
Attacker can trigger heap overflow via crafted tab stop arguments in unexpand, potentially leading to code execution or crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-56392?
CVE-2026-56392 is a low-severity vulnerability in GNU coreutils, published on 24 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
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
Weakness: CWE-122
Which versions are affected by CVE-2026-56392?
It affects 1 product.
Linux distribution packages (18)
coreutils AlmaLinux:9 | All versions | 8.32-41.el9_8.1 |
coreutils-common AlmaLinux:9 | All versions | 8.32-41.el9_8.1 |
coreutils-single AlmaLinux:9 | All versions | 8.32-41.el9_8.1 |
coreutils Red Hat:enterprise_linux:8::baseos | All versions | 0:8.30-20.el8_10 |
coreutils-common Red Hat:enterprise_linux:8::baseos | All versions | 0:8.30-20.el8_10 |
coreutils-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.30-20.el8_10 |
coreutils-debugsource Red Hat:enterprise_linux:8::baseos | All versions | 0:8.30-20.el8_10 |
coreutils-single Red Hat:enterprise_linux:8::baseos | All versions | 0:8.30-20.el8_10 |
coreutils-single-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:8.30-20.el8_10 |
coreutils Red Hat:enterprise_linux:9::baseos | All versions | 0:8.32-41.el9_8.1 |
coreutils-debuginfo Red Hat:enterprise_linux:9::baseos | All versions | 0:8.32-41.el9_8.1 |
coreutils-debugsource Red Hat:enterprise_linux:9::baseos | All versions | 0:8.32-41.el9_8.1 |
coreutils-single Red Hat:enterprise_linux:9::baseos | All versions | 0:8.32-41.el9_8.1 |
coreutils-single-debuginfo Red Hat:enterprise_linux:9::baseos | All versions | 0:8.32-41.el9_8.1 |
coreutils Red Hat:hummingbird:1 | All versions | 0:9.11-5.hum1 |
coreutils-common Red Hat:hummingbird:1 | All versions | 0:9.11-5.hum1 |
coreutils-single Red Hat:hummingbird:1 | All versions | 0:9.11-5.hum1 |
coreutils Rocky Linux:9 | All versions | 0:8.32-41.el9_8.1 |
Products include Gnu Coreutils.
How do I fix CVE-2026-56392?
Apply the vendor's patch.
Is CVE-2026-56392 being exploited?
There is no known exploitation of CVE-2026-56392 in the wild and no public exploit code.
Other vulnerabilities in GNU coreutils
Sources
Also known as ALSA-2026:66403, CLSA-2026-1788177078, CLSA-2026-1788268556, DEBIAN-CVE-2026-56392, GHSA-g24f-m2hx-pfgx, JLSEC-2026-1196 and 9 more.