CVE-2026-39979

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.

References

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-39979.json

https://github.com/jqlang/jq/security/advisories/GHSA-2hhh-px8h-355p

https://github.com/jqlang/jq/commit/2f09060afab23fe9390cce7cb860b10416e1bf5f

https://bugzilla.redhat.com/show_bug.cgi?id=2458077

https://access.redhat.com/security/cve/CVE-2026-39979

https://access.redhat.com/errata/RHSA-2026:8579

https://access.redhat.com/errata/RHSA-2026:30089

https://access.redhat.com/errata/RHSA-2026:30088

https://access.redhat.com/errata/RHSA-2026:30087

https://access.redhat.com/errata/RHSA-2026:30078

https://access.redhat.com/errata/RHSA-2026:28887

https://access.redhat.com/errata/RHSA-2026:26542

https://access.redhat.com/errata/RHSA-2026:26528

https://access.redhat.com/errata/RHSA-2026:25181

https://access.redhat.com/errata/RHSA-2026:25096

https://access.redhat.com/errata/RHSA-2026:25044

https://access.redhat.com/errata/RHSA-2026:23245

https://access.redhat.com/errata/RHSA-2026:23233

https://access.redhat.com/errata/RHSA-2026:19365

https://access.redhat.com/errata/RHSA-2026:19151

https://access.redhat.com/errata/RHSA-2026:18048

https://access.redhat.com/errata/RHSA-2026:18047

https://access.redhat.com/errata/RHSA-2026:18046

https://access.redhat.com/errata/RHSA-2026:18045

https://access.redhat.com/errata/RHSA-2026:18044

https://access.redhat.com/errata/RHSA-2026:18043

https://access.redhat.com/errata/RHSA-2026:18042

https://access.redhat.com/errata/RHSA-2026:18040

https://access.redhat.com/errata/RHSA-2026:16693

https://access.redhat.com/errata/RHSA-2026:16692

https://access.redhat.com/errata/RHSA-2026:16252

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS