Is CVE-2026-40164 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-40164 being exploited in the wild.

How severe is CVE-2026-40164?

High severity, with a CVSS score of 7.5, published 14 April 2026.

Is there a fix for CVE-2026-40164?

A patch was published on 2026-05-12: Red Hat released security updates for RHEL 8 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-40164 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-40164?

Check whether you run Jqlang Jq at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-40164: jqlang jq denial of service via predictable MurmurHash3 seed

CVE-2026-40164 · Severity: high · CVSS 7.5 · Published 2026-04-14

jq is a widely used command-line tool for processing and transforming JSON data in automated environments like CI/CD pipelines and web services. A vulnerability in how it handles data allows an attacker to send a specially crafted, small JSON file that causes the tool to consume excessive CPU resources. This can lead to a denial-of-service condition, stalling automated workflows or crashing services that rely on jq to process external data.

Technologies: Jqlang Jq. Vendors: Jqlang.

Quick answers

Is CVE-2026-40164 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-40164 being exploited in the wild.
How severe is CVE-2026-40164?: High severity, with a CVSS score of 7.5, published 14 April 2026.
Which products and versions are affected?: Jqlang Jq <= 1.8.1.
Is there a fix for CVE-2026-40164?: A patch was published on 2026-05-12: Red Hat released security updates for RHEL 8 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-40164 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-40164?: Check whether you run Jqlang Jq at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is an algorithmic complexity denial-of-service (DoS) rooted in the use of a hardcoded seed (0x432A9843) for the MurmurHash3 algorithm in src/jv.c. Because the seed is static and publicly known, an attacker can precompute a set of JSON keys that result in hash collisions. When jq processes a JSON object containing these keys, the internal hash table lookups degrade from constant time O(1) to linear time O(n), resulting in quadratic O(n²) overall complexity for jq expressions. This allows a relatively small payload (approx. 100KB) to cause significant CPU exhaustion. The issue is fixed in version 1.8.2 by randomizing the hash seed at process startup.

Affected products

jqlang jq <= 1.8.1
Red Hat Red Hat Enterprise Linux 8 8.10
Red Hat Red Hat OpenShift Container Platform 4.12, 4.13, 4.15

Timeline

2026-04-13: advisory: GitHub Security Advisory GHSA-wwj8-gxm6-jc29 published
2026-04-14: disclosed: CVE-2026-40164 published
2026-05-12: patched: Red Hat released security updates for RHEL 8

References

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