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.

Weakness classification

• security-advisories@github.com: CWE-125
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-125

Primary references

• security-advisories@github.com — Patch
• security-advisories@github.com — Exploit, Vendor Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory
• 0b0ca135-0b70-47e7-9f44-1890c2a1c46c — Third Party Advisory