CVE-2026-40469: Heap buffer overflow in gawk

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-13 · updated 2026-10-24
Weakness: CWE-190

Description

Integer overflow vulnerability has been found in "builtin.c" program file of gawk (do_sub() routine). This issue could be used to overwrite gawk heap metadata and objects causing the program to crash. It affects 32-bit builds of gawk in versions 5.4.0 and below.

Affected products

GNU gawk: through 5.4.0

References

https://cert.pl/en/posts/2026/07/CVE-2026-40467
https://cgit.git.savannah.gnu.org/cgit/gawk.git/commit/?id=ae1b2d508f46913269a9e62aceda3636afe8147b

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