Skip to main content
Public proof of conceptFix available

CVE-2026-40164

jq: Algorithmic complexity DoS via hardcoded MurmurHash3 seed

A public proof of concept exists; no exploitation attested.

  • Published2026-04-14
  • WeaknessCWE-328 · CWE-341 · CWE-407

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-04-1400:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-40164?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-40164?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • jqAlmaLinux:10all versions · fixed in 1.7.1-11.el10_2.2and 1 other package
  • jqAlmaLinux:10all versions · fixed in 1.7.1-11.el10_1.0.2and 1 other package
  • jqAlmaLinux:9all versions · fixed in 1.6-19.el9_8.2and 1 other package
  • jqAlmaLinux:9all versions · fixed in 1.6-19.el9_7.0.2and 1 other package
  • jqAlmaLinux:8all versions · fixed in 1.6-12.el8_10and 1 other package

Vendor advisories

  • CVE-2026-40164 Red Hat Product Security363 products fixed · 1 known affected

    jq: jq: Denial of Service via crafted JSON object causing hash collisions

    openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4

  • RHSA-2026:74674 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat AI Base Images 3.4.3 (Neuron)

  • RHSA-2026:34098 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.17.55 bug fix and security update

  • RHSA-2026:28887 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: OpenShift Container Platform 4.14.68 bug fix and security update

  • RHSA-2026:30089 Red Hat Product Security2 products fixed

    Red Hat Security Advisory: Red Hat AI Inference Server 3.3.5 (CUDA)

  • RHSA-2026:30088 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat AI Inference Server 3.3.5 (ROCm)

23 more advisories

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2026:74674 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:74674
  2. Vendor fix Red Hat Product Security RHSA-2026:34098 · 4 productsFor OpenShift Container Platform 4.17 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  3. Vendor fix Red Hat Product Security RHSA-2026:28887 · 4 productsFor OpenShift Container Platform 4.14 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  4. Vendor fix Red Hat Product Security RHSA-2026:30089 · 2 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30089
  5. Vendor fix Red Hat Product Security RHSA-2026:30088 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:30088
  6. Vendor fix Red Hat Product Security RHSA-2026:30087 · 3 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30087

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionpoc2026-04-14
  • OpenCVESSVC decisionpoc—
  • CNACVSS 3.17.5read 2026-10-23
  • CNAweakness (CWE)CWE-328, CWE-341, CWE-407read 2026-10-23
  • FIRST EPSSEPSS score0.6 %2026-10-23
  • OSVaffected packages—
  • Microsoft MSRCadvisory—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2026-04-14
Last Modified
2026-07-15
NVD status
Deferred
MSRC Title
jq: Algorithmic complexity DoS via hardcoded MurmurHash3 seed

Frequently asked questions

What is CVE-2026-40164?

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.

Is CVE-2026-40164 actively exploited?

A proof-of-concept exploit exists for CVE-2026-40164, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-40164?

CVE-2026-40164 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Running jq? Hear about its next vulnerability

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this productCISA KEV additions, October 2026Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database