Medium severity · published Apr 13, 2026
CVE-2026-39979
jq: Out-of-Bounds Read in jv_parse_sized() Error Formatting for Non-NUL-Terminated Counted Buffers
6.5
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 46% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JQ
jq · jqlang
< 2f09060afab23fe9390cce7cb860b10416e1bf5f · source: vendor, NVD
AI
AI Inference Server · Redhat
3.2.0 before 3.2.2; 3.3.0 before 3.3.5 · source: NVD
AA
Ansible Automation Platform · Redhat
2.0 · source: NVD
CS
Ceph Storage · Redhat
4.0 · source: NVD
CL
Codeready Linux Builder · Redhat
8.0; 9.0; 10.0 · source: NVD
CL
Codeready Linux Builder Eus · Redhat
9.4; 9.6; 10.0 · source: NVD
EL
Enterprise Linux · Redhat
8.0; 9.0; 10.0 · source: NVD
EL
Enterprise Linux Aus · Redhat
8.4; 8.6 · source: NVD
EL
Enterprise Linux Eus · Redhat
8.4; 9.4; 9.6; 10.0 · source: NVD
EL
Enterprise Linux Tus · Redhat
8.6; 8.8 · source: NVD
EL
Enterprise Linux Update Services For Sap Solutions · Redhat
8.6; 8.8; 9.0; 9.2 · source: NVD
HI
Hardened Images · Redhat
All versions, or not specified · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39979
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-39979
Patch
https://github.com/jqlang/jq/commit/2f09060afab23fe9390cce7cb860b10416e1bf5f
Exploit
https://github.com/jqlang/jq/security/advisories/GHSA-2hhh-px8h-355p
Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:16252
Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:16692
Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:16693
Third Party Advisory
https://access.redhat.com/errata/RHSA-2026:18040
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