jqlang jq up to 1.8.1 jvp_string_append/jvp_string_copy_replace_bad heap-based overflow

Summaryinfo

A vulnerability categorized as critical has been discovered in jqlang jq up to 1.8.1. Affected by this issue is the function jvp_string_append/jvp_string_copy_replace_bad. The manipulation results in heap-based overflow. This vulnerability is cataloged as CVE-2026-32316. The attack may be launched remotely. There is no exploit available. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability, which was classified as critical, was found in jqlang jq up to 1.8.1. Affected is the function jvp_string_append/jvp_string_copy_replace_bad. The manipulation with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

jq is a command-line JSON processor. An integer overflow vulnerability exists through version 1.8.1 within the jvp_string_append() and jvp_string_copy_replace_bad functions, where concatenating strings with a combined length exceeding 2^31 bytes causes a 32-bit unsigned integer overflow in the buffer allocation size calculation, resulting in a drastically undersized heap buffer. Subsequent memory copy operations then write the full string data into this undersized buffer, causing a heap buffer overflow classified as CWE-190 (Integer Overflow) leading to CWE-122 (Heap-based Buffer Overflow). Any system evaluating untrusted jq queries is affected, as an attacker can crash the process or potentially achieve further exploitation through heap corruption by crafting queries that produce extremely large strings. The root cause is the absence of string size bounds checking, unlike arrays and objects which already have size limits. The issue has been addressed in commit e47e56d226519635768e6aab2f38f0ab037c09e5.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-32316 since 03/11/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available.

Applying the patch e47e56d226519635768e6aab2f38f0ab037c09e5 is able to eliminate this problem. The bugfix is ready for download at github.com.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• jqlang

Name

• jq

Version

• 1.8.0
• 1.8.1

License

• open-source

Website

• Product: https://github.com/jqlang/jq/

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