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VulnerabilityPublished Updated

CVE-2026-39956: jqlang jq · Out-of-bounds Read

Affects jqlang jqSource CVE Database V5

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Not known to be exploited · CVSS 6.1 Medium : upgrade to 1.8.2 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
6.1Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.8.2
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade jqlang jq to 1.8.2.

Affected software

ProductAffectedFixed in
jqlangjqAffected
  • <1.8.2
Fixed in
  • 1.8.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch fixing this vulnerability has been committed in jq at commit fdf8ef0f0810e3d365cdd5160de43db46f57ed03. Users should upgrade to a version including this commit or later. Until patched, avoid evaluating untrusted jq filters in release builds. Patch status is confirmed by the vendor commit reference.

Description

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.

References

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