# CVE-2026-39956: jq is a command-line JSON processor. Prior to version 1.8.2, the _strindices builtin in jq's src/builtin.c passes its…

Source: https://junglewise.ai/threats/cve-2026-39956-jq-is-a-command-line-json-processor-prior-to-version-1-8-2-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-13  
License: CC BY 4.0 with a link back

CVE-2026-39956 · Severity: medium · CVSS 6.1 · Published 2026-04-13

jq is a command-line JSON processor. Prior to version 1.8.2, the _strindices builtin in jq's src/builtin.c passes its arguments directly to jv_string_indexes() without verifying they are strings, and jv_string_indexes() in src/jv.c relies solely on assert() checks that are stripped in release builds compiled with -DNDEBUG. This allows an attacker to crash jq trivially with input like _strindices(0), and by crafting a numeric value whose IEEE-754 bit pattern maps to a chosen pointer, achieve a controlled pointer dereference and limited memory read/probe primitive. Any deployment that evaluates untrusted jq filters against a release build is vulnerable. This issue has been patched in commit fdf8ef0f0810e3d365cdd5160de43db46f57ed03, which is part of version 1.8.2.

Technologies: [Jqlang Jq](https://junglewise.ai/threats/technologies/jq). Vendors: [Jqlang](https://junglewise.ai/threats/vendors/jqlang).

## Quick answers

**Is CVE-2026-39956 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-39956 being exploited in the wild.

**How severe is CVE-2026-39956?** Medium severity, with a CVSS score of 6.1, published 13 April 2026.

**Which products and versions are affected?** Jqlang Jq. The advisory does not name versions.

**Is there a fix for CVE-2026-39956?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2026-39956?** Check whether you run Jqlang Jq. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Jqlang Jq

## Related threats

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- [jqlang jq uncontrolled recursion in module loader](https://junglewise.ai/threats/cve-2026-44777-jqlang-jq-uncontrolled-recursion-in-module-loader)
- [jqlang jq stack overflow in jv_object_merge_recursive](https://junglewise.ai/threats/cve-2026-43896-jqlang-jq-stack-overflow-in-jv-object-merge-recursive)