CVE-2026-40164Public exploitNetwork attack vector

CPU exhaustion via predictable hash collisions

Published Apr 13, 2026 · Updated Apr 13, 2026

Algorithmic complexity denial of service in jqlang jq 1.8.1 and earlier allows remote attackers to exhaust CPU via crafted JSON objects. The object hash-table code in src/jv.c seeds MurmurHash3 with the public constant 0x432A9843, enabling offline construction of colliding keys that reduce lookups from O(1) to O(n). Processing a roughly 100 KB collision set requires no privileges or user interaction and turns ordinary jq expressions into O(n²) work, interrupting service through CPU exhaustion.

CVSS severity7.5
High
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic complexity denial of service in jqlang jq 1.8.1 and earlier allows remote attackers to exhaust CPU via crafted JSON objects. The object hash-table code in src/jv.c seeds MurmurHash3 with the public constant 0x432A9843, enabling offline construction of colliding keys that reduce lookups from O(1) to O(n). Processing a roughly 100 KB collision set requires no privileges or user interaction and turns ordinary jq expressions into O(n²) work, interrupting service through CPU exhaustion.

The record

CVE
CVE-2026-40164
Published
Apr 13, 2026
Updated
Apr 13, 2026
Vendor
jqlang
Product
jq
Classifications
CWE-407, CWE-328, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0c7d133c3c7e37c00b6d46b658a02244fdd3c784

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

jqlang · jqversion=< 0c7d133c3c7e37c00b6d46b658a02244fdd3c784

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Red Hat SADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-407Inefficient Algorithmic Complexity
CWE-328Use of Weak Hash
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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