# 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.

- Web page: https://patchblox.com/security/cve/CVE-2026-39979
- Priority: High
- CVSS: 8.2 (Moderate)
- EPSS: 0.0056
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 13, 2026
- Weakness: Out-of-bounds Read
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | jq Debian 12.15 (bookworm) | 1.6-2.1+deb12u2 | [DEBIAN-CVE-2026-39979](https://patchblox.com/security/data/fix/linux/debian-cve-2026-39979.md) | Apr 13, 2026 |
| Linux | jq Debian 13.5 (trixie) | 1.7.1-6+deb13u2 | [DEBIAN-CVE-2026-39979](https://patchblox.com/security/data/fix/linux/debian-cve-2026-39979.md) | Apr 13, 2026 |
| Linux | jq Debian 14 | 1.8.1-5 | [DEBIAN-CVE-2026-39979](https://patchblox.com/security/data/fix/linux/debian-cve-2026-39979.md) | Apr 13, 2026 |
| Linux | jq Fedora 43 | 1.8.1-3.fc43 | [FEDORA-2026-4E57162966](https://patchblox.com/security/data/fix/linux/fedora-2026-4e57162966.md) | Apr 16, 2026 |
| Linux | jq RHEL 10 | 1.7.1-8.el10_0.3 | [RHSA-2026:18040](https://patchblox.com/security/data/fix/linux/rhsa-2026-18040.md) | Apr 13, 2026 |
| Linux | jq RHEL 8 | 0:1.6-12.el8_10 | [RHSA-2026:16252](https://patchblox.com/security/data/fix/linux/rhsa-2026-16252.md) | May 15, 2026 |
| Linux | jq RHEL 9 | 0:1.6-19.el9_8.2 | [RHSA-2026:19365](https://patchblox.com/security/data/fix/linux/rhsa-2026-19365.md) | May 15, 2026 |
| Linux | jq Ubuntu 18.04.6 LTS (bionic) | 1.5+dfsg-2ubuntu0.1~esm2 | [jq 1.5+dfsg-2ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-jq-1.5-dfsg-2ubuntu0.1-esm2.md) | Apr 13, 2026 |
| Linux | jq Ubuntu 20.04 LTS (focal) | 1.6-1ubuntu0.20.04.1+esm2 | [jq 1.6-1ubuntu0.20.04.1+esm2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-jq-1.6-1ubuntu0.20.04.1-esm2.md) | Apr 13, 2026 |
| Linux | jq Ubuntu 22.04.1 LTS (jammy) | 1.6-2.1ubuntu3.2 | [jq 1.6-2.1ubuntu3.2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-jq-1.6-2.1ubuntu3.2.md) | Apr 13, 2026 |
| Linux | jq Ubuntu 24.04.5 LTS (noble) | 1.7.1-3ubuntu0.24.04.2 | [jq 1.7.1-3ubuntu0.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-jq-1.7.1-3ubuntu0.24.04.2.md) | Apr 13, 2026 |
| Linux | jq Ubuntu 25.10 (questing) | 1.8.1-3ubuntu1.1 | [jq 1.8.1-3ubuntu1.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-jq-1.8.1-3ubuntu1.1.md) | Apr 13, 2026 |
| Linux | jq Ubuntu 26.04.1 LTS (resolute) | 1.8.1-4ubuntu2 | [jq 1.8.1-4ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-jq-1.8.1-4ubuntu2.md) | Apr 13, 2026 |
| Linux | jq almalinux 10 | 1.7.1-11.el10_2.2 | [ALSA-2026:19151](https://patchblox.com/security/data/fix/linux/alsa-2026-19151.md) | May 19, 2026 |
| Linux | jq almalinux 8 | 1.6-12.el8_10 | [ALSA-2026:16252](https://patchblox.com/security/data/fix/linux/alsa-2026-16252.md) | May 12, 2026 |
| Linux | jq almalinux 9 | 1.6-19.el9_8.2 | [ALSA-2026:19365](https://patchblox.com/security/data/fix/linux/alsa-2026-19365.md) | May 19, 2026 |
| Linux | jq amzn 2023 | 1.8.1-59.amzn2023 | [ALAS2023-2026-1815](https://patchblox.com/security/data/fix/linux/alas2023-2026-1815.md) | Jun 8, 2026 |
| Linux | jq ol 10 | 0:1.7.1-11.el10_1.0.2 | [ELSA-2026-16692](https://patchblox.com/security/data/fix/linux/elsa-2026-16692.md) | May 13, 2026 |
| Linux | jq ol 8 | 0:1.6-12.el8_10 | [ELSA-2026-16252](https://patchblox.com/security/data/fix/linux/elsa-2026-16252.md) | May 13, 2026 |
| Linux | jq ol 9 | 0:1.6-19.el9_7.0.2 | [ELSA-2026-16693](https://patchblox.com/security/data/fix/linux/elsa-2026-16693.md) | May 13, 2026 |
| Linux | jq opensuse-leap 16.0 | 1.7.1-160000.3.1 | [OPENSUSE-SU-2026:21248-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21248-1.md) | Jul 7, 2026 |
| Linux | jq rocky 10 | 0:1.7.1-11.el10_2.2 | [RLSA-2026:19151](https://patchblox.com/security/data/fix/linux/rlsa-2026-19151.md) | May 29, 2026 |
| Linux | jq rocky 8 | 0:1.6-12.el8_10 | [RLSA-2026:16252](https://patchblox.com/security/data/fix/linux/rlsa-2026-16252.md) | May 14, 2026 |
| Linux | jq rocky 9 | 0:1.6-19.el9_8.2 | [RLSA-2026:19365](https://patchblox.com/security/data/fix/linux/rlsa-2026-19365.md) | May 28, 2026 |
| Linux | jq sles 15.7 | 1.6-150000.3.20.1 | [SUSE-SU-2026:2983-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2983-1.md) | Jul 14, 2026 |
| Linux | jq sles 16.0 | 1.7.1-160000.3.1 | [SUSE-SU-2026:22566-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22566-1.md) | Jul 7, 2026 |
| Linux | jq-debuginfo Fedora 43 | 1.8.1-3.fc43 | [FEDORA-2026-4E57162966](https://patchblox.com/security/data/fix/linux/fedora-2026-4e57162966.md) | Apr 16, 2026 |
| Linux | jq-debuginfo amzn 2023 | 1.8.1-59.amzn2023 | [ALAS2023-2026-1815](https://patchblox.com/security/data/fix/linux/alas2023-2026-1815.md) | Jun 8, 2026 |
| Linux | jq-debugsource Fedora 43 | 1.8.1-3.fc43 | [FEDORA-2026-4E57162966](https://patchblox.com/security/data/fix/linux/fedora-2026-4e57162966.md) | Apr 16, 2026 |
| Linux | jq-debugsource amzn 2023 | 1.8.1-59.amzn2023 | [ALAS2023-2026-1815](https://patchblox.com/security/data/fix/linux/alas2023-2026-1815.md) | Jun 8, 2026 |
| Linux | jq-devel Fedora 43 | 1.8.1-3.fc43 | [FEDORA-2026-4E57162966](https://patchblox.com/security/data/fix/linux/fedora-2026-4e57162966.md) | Apr 16, 2026 |
| Linux | jq-devel RHEL 8 | 0:1.6-12.el8_10 | [RHSA-2026:16252](https://patchblox.com/security/data/fix/linux/rhsa-2026-16252.md) | May 15, 2026 |
| Linux | jq-devel RHEL 9 | 0:1.6-19.el9_8.2 | [RHSA-2026:19365](https://patchblox.com/security/data/fix/linux/rhsa-2026-19365.md) | May 15, 2026 |
| Linux | jq-devel almalinux 10 | 1.7.1-11.el10_2.2 | [ALSA-2026:19151](https://patchblox.com/security/data/fix/linux/alsa-2026-19151.md) | May 19, 2026 |
| Linux | jq-devel almalinux 8 | 1.6-12.el8_10 | [ALSA-2026:16252](https://patchblox.com/security/data/fix/linux/alsa-2026-16252.md) | May 12, 2026 |
| Linux | jq-devel almalinux 9 | 1.6-19.el9_8.2 | [ALSA-2026:19365](https://patchblox.com/security/data/fix/linux/alsa-2026-19365.md) | May 19, 2026 |
| Linux | jq-devel amzn 2023 | 1.8.1-59.amzn2023 | [ALAS2023-2026-1815](https://patchblox.com/security/data/fix/linux/alas2023-2026-1815.md) | Jun 8, 2026 |
| Linux | jq-devel ol 10 | 0:1.7.1-11.el10_1.0.2 | [ELSA-2026-16692](https://patchblox.com/security/data/fix/linux/elsa-2026-16692.md) | May 13, 2026 |
| Linux | jq-devel ol 8 | 0:1.6-12.el8_10 | [ELSA-2026-16252](https://patchblox.com/security/data/fix/linux/elsa-2026-16252.md) | May 13, 2026 |
| Linux | jq-devel ol 9 | 0:1.6-19.el9_7.0.2 | [ELSA-2026-16693](https://patchblox.com/security/data/fix/linux/elsa-2026-16693.md) | May 13, 2026 |
| Linux | libjq1 Ubuntu 18.04.6 LTS (bionic) | 1.5+dfsg-2ubuntu0.1~esm2 | [libjq1 1.5+dfsg-2ubuntu0.1~esm2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libjq1-1.5-dfsg-2ubuntu0.1-esm2.md) | Apr 13, 2026 |
| Linux | libjq1 Ubuntu 20.04 LTS (focal) | 1.6-1ubuntu0.20.04.1+esm2 | [libjq1 1.6-1ubuntu0.20.04.1+esm2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libjq1-1.6-1ubuntu0.20.04.1-esm2.md) | Apr 13, 2026 |
| Linux | libjq1 Ubuntu 22.04.1 LTS (jammy) | 1.6-2.1ubuntu3.2 | [libjq1 1.6-2.1ubuntu3.2](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libjq1-1.6-2.1ubuntu3.2.md) | Apr 13, 2026 |
| Linux | libjq1 Ubuntu 24.04.5 LTS (noble) | 1.7.1-3ubuntu0.24.04.2 | [libjq1 1.7.1-3ubuntu0.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libjq1-1.7.1-3ubuntu0.24.04.2.md) | Apr 13, 2026 |
| Linux | libjq1 Ubuntu 25.10 (questing) | 1.8.1-3ubuntu1.1 | [libjq1 1.8.1-3ubuntu1.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libjq1-1.8.1-3ubuntu1.1.md) | Apr 13, 2026 |
| Linux | libjq1 Ubuntu 26.04.1 LTS (resolute) | 1.8.1-4ubuntu2 | [libjq1 1.8.1-4ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libjq1-1.8.1-4ubuntu2.md) | Apr 13, 2026 |

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