CVE-2026-39979

jq: Out-of-Bounds Read in jv_parse_sized() Error Formatting for Non-NUL-Terminated Counted Buffers

CVE-2026-39979 is fixed in 5 products on 1 platform, first by jq 1.5+dfsg-2ubuntu0.1~esm2, released April 13, 2026. It is not reported as exploited. Patch Radar priority: High.

High
CVSS
8.2
Moderate
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0056
46th percentile

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.

Where it's fixed

ProductFixed inFixReleased
Linux
jq · Debian 12.15 (bookworm) 1.6-2.1+deb12u2 DEBIAN-CVE-2026-39979 Apr 13, 2026
jq · Debian 13.5 (trixie) 1.7.1-6+deb13u2 DEBIAN-CVE-2026-39979 Apr 13, 2026
jq · Debian 14 1.8.1-5 DEBIAN-CVE-2026-39979 Apr 13, 2026
jq · Fedora 43 1.8.1-3.fc43 FEDORA-2026-4E57162966 Apr 16, 2026
jq · RHEL 10 1.7.1-8.el10_0.3 RHSA-2026:18040 Apr 13, 2026
jq · RHEL 8 0:1.6-12.el8_10 RHSA-2026:16252 May 15, 2026
jq · RHEL 9 0:1.6-19.el9_8.2 RHSA-2026:19365 May 15, 2026
jq · Ubuntu 18.04.6 LTS (bionic) 1.5+dfsg-2ubuntu0.1~esm2 jq 1.5+dfsg-2ubuntu0.1~esm2 Apr 13, 2026
jq · Ubuntu 20.04 LTS (focal) 1.6-1ubuntu0.20.04.1+esm2 jq 1.6-1ubuntu0.20.04.1+esm2 Apr 13, 2026
jq · Ubuntu 22.04.1 LTS (jammy) 1.6-2.1ubuntu3.2 jq 1.6-2.1ubuntu3.2 Apr 13, 2026
jq · Ubuntu 24.04.5 LTS (noble) 1.7.1-3ubuntu0.24.04.2 jq 1.7.1-3ubuntu0.24.04.2 Apr 13, 2026
jq · Ubuntu 25.10 (questing) 1.8.1-3ubuntu1.1 jq 1.8.1-3ubuntu1.1 Apr 13, 2026
jq · Ubuntu 26.04.1 LTS (resolute) 1.8.1-4ubuntu2 jq 1.8.1-4ubuntu2 Apr 13, 2026
jq · almalinux 10 1.7.1-11.el10_2.2 ALSA-2026:19151 May 19, 2026
jq · almalinux 8 1.6-12.el8_10 ALSA-2026:16252 May 12, 2026
jq · almalinux 9 1.6-19.el9_8.2 ALSA-2026:19365 May 19, 2026
jq · amzn 2023 1.8.1-59.amzn2023 ALAS2023-2026-1815 Jun 8, 2026
jq · ol 10 0:1.7.1-11.el10_1.0.2 ELSA-2026-16692 May 13, 2026
jq · ol 8 0:1.6-12.el8_10 ELSA-2026-16252 May 13, 2026
jq · ol 9 0:1.6-19.el9_7.0.2 ELSA-2026-16693 May 13, 2026
jq · opensuse-leap 16.0 1.7.1-160000.3.1 OPENSUSE-SU-2026:21248-1 Jul 7, 2026
jq · rocky 10 0:1.7.1-11.el10_2.2 RLSA-2026:19151 May 29, 2026
jq · rocky 8 0:1.6-12.el8_10 RLSA-2026:16252 May 14, 2026
jq · rocky 9 0:1.6-19.el9_8.2 RLSA-2026:19365 May 28, 2026
jq · sles 15.7 1.6-150000.3.20.1 SUSE-SU-2026:2983-1 Jul 14, 2026
jq · sles 16.0 1.7.1-160000.3.1 SUSE-SU-2026:22566-1 Jul 7, 2026
jq-debuginfo · Fedora 43 1.8.1-3.fc43 FEDORA-2026-4E57162966 Apr 16, 2026
jq-debuginfo · amzn 2023 1.8.1-59.amzn2023 ALAS2023-2026-1815 Jun 8, 2026
jq-debugsource · Fedora 43 1.8.1-3.fc43 FEDORA-2026-4E57162966 Apr 16, 2026
jq-debugsource · amzn 2023 1.8.1-59.amzn2023 ALAS2023-2026-1815 Jun 8, 2026
jq-devel · Fedora 43 1.8.1-3.fc43 FEDORA-2026-4E57162966 Apr 16, 2026
jq-devel · RHEL 8 0:1.6-12.el8_10 RHSA-2026:16252 May 15, 2026
jq-devel · RHEL 9 0:1.6-19.el9_8.2 RHSA-2026:19365 May 15, 2026
jq-devel · almalinux 10 1.7.1-11.el10_2.2 ALSA-2026:19151 May 19, 2026
jq-devel · almalinux 8 1.6-12.el8_10 ALSA-2026:16252 May 12, 2026
jq-devel · almalinux 9 1.6-19.el9_8.2 ALSA-2026:19365 May 19, 2026
jq-devel · amzn 2023 1.8.1-59.amzn2023 ALAS2023-2026-1815 Jun 8, 2026
jq-devel · ol 10 0:1.7.1-11.el10_1.0.2 ELSA-2026-16692 May 13, 2026
jq-devel · ol 8 0:1.6-12.el8_10 ELSA-2026-16252 May 13, 2026
jq-devel · ol 9 0:1.6-19.el9_7.0.2 ELSA-2026-16693 May 13, 2026
libjq1 · Ubuntu 18.04.6 LTS (bionic) 1.5+dfsg-2ubuntu0.1~esm2 libjq1 1.5+dfsg-2ubuntu0.1~esm2 Apr 13, 2026
libjq1 · Ubuntu 20.04 LTS (focal) 1.6-1ubuntu0.20.04.1+esm2 libjq1 1.6-1ubuntu0.20.04.1+esm2 Apr 13, 2026
libjq1 · Ubuntu 22.04.1 LTS (jammy) 1.6-2.1ubuntu3.2 libjq1 1.6-2.1ubuntu3.2 Apr 13, 2026
libjq1 · Ubuntu 24.04.5 LTS (noble) 1.7.1-3ubuntu0.24.04.2 libjq1 1.7.1-3ubuntu0.24.04.2 Apr 13, 2026
libjq1 · Ubuntu 25.10 (questing) 1.8.1-3ubuntu1.1 libjq1 1.8.1-3ubuntu1.1 Apr 13, 2026
libjq1 · Ubuntu 26.04.1 LTS (resolute) 1.8.1-4ubuntu2 libjq1 1.8.1-4ubuntu2 Apr 13, 2026

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