CVE-2026-39979

jq is a command-line JSON processor. In commits before 2f09060afab23fe9390cce7cb860b10416e1bf5f, the jvparsesized() API in libjq accepts a counted buffer with an explicit length parameter, but its error-handling path formats the input buffer using %s in jvstringfmt(), 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 jvparsesized() with untrusted input, and depending on memory layout, can result in memory disclosure or process termination. The issue has been patched in commit 2f09060afab23fe9390cce7cb860b10416e1bf5f.

Database specific

{
    "unresolved_ranges": [
        {
            "source": "AFFECTED_FIELD",
            "extracted_events": [
                {
                    "fixed": "2f09060afab23fe9390cce7cb860b10416e1bf5f"
                }
            ]
        },
        {
            "source": "DESCRIPTION",
            "extracted_events": [
                {
                    "fixed": "2f09060afab23fe9390cce7cb860b10416e1bf5f"
                }
            ]
        }
    ],
    "cna_assigner": "GitHub_M",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39979.json",
    "cwe_ids": [
        "CWE-125"
    ]
}

References

Affected packages

Git / github.com/jqlang/jq

Affected ranges

Type

GIT

Repo

https://github.com/jqlang/jq

Events

Introduced

Fixed

2f09060afab23fe9390cce7cb860b10416e1bf5f

Database specific

{
    "source": "REFERENCES"
}

Affected versions

1.*

1.6rc2

jq-1.*

jq-1.0

jq-1.1

jq-1.2

jq-1.3

jq-1.4

jq-1.5rc1

jq-1.5rc2

jq-1.6

jq-1.6rc1

jq-1.7

jq-1.7.1

jq-1.7rc1

jq-1.7rc2

jq-1.8.0

jq-1.8.1

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-39979.json"