CVE-2026-41257

Description

jq is a command-line JSON processor. In 1.8.1 and earlier, the jq bytecode VM's data stack tracks its allocation size in a signed int. When the stack grows beyond ≈1 GiB (via deeply nested generator forks), the doubling arithmetic overflows. The wrapped value is passed to realloc and then used for a memmove with attacker-influenced offsets.

CVSS v3.1 Score

5.5

MEDIUM

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

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.02%

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

CWE-787 Out-of-bounds Write

Affected Products

Vendor	Product	Versions
jqlang	jq	< 1.8.1

References

Advisories & Patches

https://github.com/jqlang/jq/security/advisories/GHSA-4jm8-m363-4539 https://github.com/jqlang/jq/security/advisories/GHSA-4jm8-m363-4539

Exploits

https://github.com/jqlang/jq/security/advisories/GHSA-4jm8-m363-4539 https://github.com/jqlang/jq/security/advisories/GHSA-4jm8-m363-4539

Frequently Asked Questions

What is CVE-2026-41257? +

jq is a command-line JSON processor. In 1.8.1 and earlier, the jq bytecode VM's data stack tracks its allocation size in a signed int. When the stack grows beyond ≈1 GiB (via deeply nested generator forks), the doubling arithmetic overflows. The wrapped value is passed to realloc and then used for a memmove with attacker-influenced offsets. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-41257? +

CVE-2026-41257 has a CVSS v3.1 score of 5.5 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-2026-41257? +

CVE-2026-41257 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-2026-41257? +

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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