What’s Vulnerable › Vulnerabilities

CVE-2026-43894: jq: Wild stack write via signed-integer overflow in decNumber D2U() macro

• Severity: medium (CVSS 5.5 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: yes
• Published: 2026-05-11 · updated 2026-10-26
• Weakness: CWE-190

Description

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 products

• jqlang jq: through 1.8.1

References

• https://github.com/jqlang/jq/security/advisories/GHSA-5v7p-2r57-2g4g
• https://github.com/jqlang/jq/security/advisories/GHSA-5v7p-2r57-2g4g

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