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.
Published: 2026-04-13
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service via excessive CPU usage caused by hash collision exploitation
Action: Immediate Patch
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8202-2 jq vulnerabilities
History

Wed, 15 Apr 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-341
References
Metrics threat_severity

None

threat_severity

Important


Tue, 14 Apr 2026 22:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 14 Apr 2026 16:30:00 +0000

Type Values Removed Values Added
First Time appeared Jqlang
Jqlang jq
Vendors & Products Jqlang
Jqlang jq

Tue, 14 Apr 2026 00:00:00 +0000

Type Values Removed Values Added
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.
Title jq: Algorithmic complexity DoS via hardcoded MurmurHash3 seed
Weaknesses CWE-328
CWE-407
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-04-14T19:27:38.916Z

Reserved: 2026-04-09T19:31:56.014Z

Link: CVE-2026-40164

cve-icon Vulnrichment

Updated: 2026-04-14T19:23:14.106Z

cve-icon NVD

Status : Deferred

Published: 2026-04-14T00:16:07.360

Modified: 2026-04-28T21:15:56.987

Link: CVE-2026-40164

cve-icon Redhat

Severity : Important

Publid Date: 2026-04-13T23:40:12Z

Links: CVE-2026-40164 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-15T15:45:07Z

Weaknesses