Skip to main content
Public proof of conceptFix available

CVE-2026-39979

A public proof of concept exists; no exploitation attested.

  • Published2026-04-13
  • Fixed in2026-04-12
  • WeaknessCWE-125

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. In commits before 2f09060afab23fe9390cce7cb860b10416e1bf5f, the jv_parse_sized() API in libjq accepts a counted buffer with an explicit length parameter, but its error-handling path formats the input buffer using %s in jv_string_fmt(), which reads until a NUL terminator is found rather than respecting the caller-supplied length. This means that when malformed JSON is passed in a non-NUL-terminated buffer, the error construction logic performs an out-of-bounds read past the end of the buffer. The vulnerability is reachable by any libjq consumer calling jv_parse_sized() with untrusted input, and depending on memory layout, can result in memory disclosure or process termination. The issue has been patched in commit 2f09060afab23fe9390cce7cb860b10416e1bf5f.

Timeline

dates in UTC
  1. 2026-04-1323:16CVE 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-2026-39979?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-39979?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Jqlang jq
BranchAffectedFixed in
2026.x< 2026-04-122026-04-12

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

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-2026-39979 Red Hat Product Security363 products fixed · 2 known affected

    jq: out-of-bounds read in jv_parse_sized() on error formatting for non-NUL-terminated buffers

    ansible-automation-platform-26/controller-rhel9 as a component of Red Hat Ansible Automation Platform 2 · jq.src as a component of Red Hat Ceph Storage 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. Update Jqlang jq to 2026-04-12
  2. Vendor fix Red Hat Product Security RHSA-2026:74674 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:74674
  3. 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.…
  4. 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.…
  5. Vendor fix Red Hat Product Security RHSA-2026:30089 · 2 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30089
  6. Vendor fix Red Hat Product Security RHSA-2026:30088 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:30088
  7. Vendor fix Red Hat Product Security RHSA-2026:30087 · 3 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30087

Advisories and patches

Detection

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

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2026-04-13
Last Modified
2026-07-15
NVD status
Undergoing Analysis
MSRC Title
jq: Out-of-Bounds Read in jv_parse_sized() Error Formatting for Non-NUL-Terminated Counted Buffers

Frequently asked questions

What is CVE-2026-39979?

jq is a command-line JSON processor. In commits before 2f09060afab23fe9390cce7cb860b10416e1bf5f, the jv_parse_sized() API in libjq accepts a counted buffer with an explicit length parameter, but its error-handling path formats the input buffer using %s in jv_string_fmt(), which reads until a NUL terminator is found rather than respecting the caller-supplied length. This means that when malformed JSON is passed in a non-NUL-terminated buffer, the error construction logic performs an out-of-bounds read past the end of the buffer. The vulnerability is reachable by any libjq consumer calling jv_parse_sized() with untrusted input, and depending on memory layout, can result in memory disclosure or process termination. The issue has been patched in commit 2f09060afab23fe9390cce7cb860b10416e1bf5f.

Is CVE-2026-39979 actively exploited?

A proof-of-concept exploit exists for CVE-2026-39979, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-39979?

CVE-2026-39979 has a CVSS v3 base score of 6.5 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L.

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