CVE-2026-39979
MediumCVSS 6.5Exploitation Probability (EPSS)
Low risk43th percentile - higher than 43% of all known CVEs
Summary
In the libjq library (part of the jq tool), the jv_parse_sized() function has an out-of-bounds read vulnerability. When processing malformed JSON in a non-NUL-terminated buffer, the error formatting function uses %s which reads until a NUL terminator, ignoring the caller-supplied length.
Risk Assessment
An attacker can exploit this vulnerability to disclose memory contents or cause a process crash, posing a risk to system confidentiality and availability.
Recommendation
Immediately update libjq to a version containing commit 2f09060afab23fe9390cce7cb860b10416e1bf5f or later. If an update is not possible, restrict access to jv_parse_sized() for untrusted input.
Original NVD description (English source)
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.