CVE-2026-43894

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).

CVSS v3.1 Score

6.2

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.03%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-190 Integer Overflow

Affected Products

Vendor	Product	Versions
jqlang	jq	< 1.8.1

References

Advisories & Patches

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

Exploits

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

Frequently Asked Questions

What is 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). It has a CVSS v3.1 base score of 6.2 (MEDIUM).

How severe is CVE-2026-43894? +

CVE-2026-43894 has a CVSS v3.1 score of 6.2 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-43894? +

CVE-2026-43894 affects products from jqlang, specifically: jq. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-43894? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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