CVE-2026-40164 Details
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.
A denial-of-service vulnerability has been identified in jq, a command-line JSON processor, affecting all versions prior to the latest commit. The issue arises from the use of MurmurHash3 with a hardcoded seed, which allows attackers to precompute hash collisions. By sending a crafted JSON object of approximately 100 KB, keys can be manipulated to hash into the same bucket, causing hash table lookups to degrade from constant time to linear time. This exploitation transforms jq operations into quadratic time complexity, leading to significant CPU exhaustion. Common use cases such as CI/CD pipelines, web services, and data processing scripts are particularly impacted.
The vulnerability has been patched by randomizing the hash seed, preventing the precomputation of collisions. Users should update to the latest version of jq where this fix is applied.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Apr 14, 2026CISA-ADP
Assessed Apr 14, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-328 | Use of Weak Hash | [email protected] |
| CWE-341 | Predictable from Observable State | redhat-SADP |
| CWE-407 | Inefficient Algorithmic Complexity | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| jq | < 0c7d133c3c7e37c00b6d46b658a02244fdd3c784 |
CPE
Remediation
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Change History
7 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 15, 2026 | CVE Modified | redhat-SADP |
| Jul 10, 2026 | CVE Modified | redhat-SADP |
| Jul 2, 2026 | CVE Modified | redhat-SADP |
| Jun 30, 2026 | CVE Modified | redhat-SADP |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Apr 14, 2026 | New CVE Received | [email protected] |