Vulnerability Details CVE-2026-39979
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 15.0%
CVSS Severity
CVSS v3 Score 6.5
References
Products affected by CVE-2026-39979
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cpe:2.3:a:jqlang:jq:1.0
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cpe:2.3:a:jqlang:jq:1.1
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cpe:2.3:a:jqlang:jq:1.2
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cpe:2.3:a:jqlang:jq:1.3
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cpe:2.3:a:jqlang:jq:1.4
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cpe:2.3:a:jqlang:jq:1.5
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cpe:2.3:a:jqlang:jq:1.6
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cpe:2.3:a:jqlang:jq:1.7
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cpe:2.3:a:jqlang:jq:1.7-37-g88f01a7
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cpe:2.3:a:jqlang:jq:1.7.1