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VulnerabilityPublished Updated

CVE-2026-40164: jqlang jq · Use of Weak Hash

Affects jqlang jqSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 29 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
jqlangjqAffected
  • =< 0c7d133c3c7e37c00b6d46b658a02244fdd3c784
Fixed in–

AI-suggested

A patch fixing this vulnerability is available in jq as of commit 0c7d133c3c7e37c00b6d46b658a02244fdd3c784. Users should update jq to a version including this commit. Red Hat has released security advisories and updates addressing this issue for their affected products, including OpenShift Container Platform 4.12. Users of Red Hat products should apply these updates promptly. Patch status is confirmed by vendor advisories. No additional mitigations are specified.

Description

jq is a command-line JSON processor. Before commit 0c7d133c3c7e37c00b6d46b658a02244fdd3c784, jq used MurmurHash3 with a hardcoded, publicly visible seed (0x432A9843) for all JSON object hash table operations, which allowed an attacker to precompute key collisions offline. By supplying a crafted JSON object (~100 KB) where all keys hashed to the same bucket, hash table lookups degraded from O(1) to O(n), turning any jq expression into an O(n²) operation and causing significant CPU exhaustion. This affected common jq use cases such as CI/CD pipelines, web services, and data processing scripts, and was far more practical to exploit than existing heap overflow issues since it required only a small payload. This issue has been patched in commit 0c7d133c3c7e37c00b6d46b658a02244fdd3c784.

References

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