Integer overflow in Jqlang Jq
CVE-2026-43894
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).
Vulnerability class: Integer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.2 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.002 (4.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 4.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: -0.000
Affected products
- Jqlang Jq — versions <= 1.8.1
Weakness classification (CWE)
References
- github.com/jqlang/jq/security/advisories/GHSA-5v7p-2r57-2g4g (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-43894?
- CVE-2026-43894 is a medium-severity vulnerability in Jqlang Jq, classified under Integer Overflow or Wraparound. CVSS score: 6.2/10. Published 2026-05-11.
- How severe is CVE-2026-43894?
- Medium severity. CVSS v3 base score is 6.2 out of 10.