🛡️ CVE-2026-39979 — jq
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.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability low.
Weakness class
CVE-2026-39979 is classified as CWE-125: Out-of-bounds Read. The code reads past the limits of a buffer, exposing adjacent memory contents or crashing the process.
Affected software
CVE-2026-39979 is recorded against 1 package.
- jq (fixed in 2026-04-12)
Timeline and source
Published on 13 April 2026 and last revised on 15 July 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from NVD.
References
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CVE-2026-39979 on other distributions
Each distribution ships its own build and its own fixed version. Pick the one you run:
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| jq | — | 2026-04-12 |
References
Similar Threats
- Unknown ALSA-2026:19151
- Unknown ALSA-2026:19365
- Unknown ALSA-2026:16692
- Unknown ALSA-2026:16693
- Unknown ALSA-2026:16252
More CVE 2026 advisories
Browse all of CVE 2026 in the advisory index.
Exploit Protection
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CVE-2026-39979 carries CVSS 6.5 Medium rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.
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