CVE-2026-43894: jq: Wild stack write via signed-integer overflow in decNumber D2U() macro
jq is a command-line JSON processor. In 1.8.1 and earlier, when decNumberFromString is given a number literal of INT_MAX-1 (2147483646) digits, the D2U() macro overflows during signed-int arithmetic. The wrapped negative value bypasses the heap-allocation size check, causes the function to use a 30-byte stack buffer, and then writes ≈715 million 16-bit units (≈1.4 GiB) at an offset 1.43 GiB below the stack frame. The written content is fully attacker-controlled (the parsed decimal digits, packed 3-per-unit).
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-43894?
CVE-2026-43894 is classified as a high severity vulnerability due to its potential for causing a wild stack write.
How do I fix CVE-2026-43894?
To fix CVE-2026-43894, upgrade jq to version 1.8.2 or later.
What software versions are affected by CVE-2026-43894?
CVE-2026-43894 affects jq versions up to and including 1.8.1.
What types of applications may be impacted by CVE-2026-43894?
Applications using vulnerable versions of jq for JSON processing may be impacted by CVE-2026-43894.
Is CVE-2026-43894 a local or remote threat?
CVE-2026-43894 represents a local threat, as it requires the execution of maliciously crafted JSON input.