Buffer overflow in Jqlang Jq
CVE-2026-49839
jq is a command-line JSON processor. Prior to 1.8.2,` jq --rawfile` can turn a handled oversized-string error into invalid-state reuse and a real heap out-of-bounds write in assertion-disabled builds. When jv_load_file(raw=1) reads an attacker-controlled file, it repeatedly appends file chunks to the same jv string accumulator. Once jv_string_append_buf() returns jv_invalid_with_msg("String too long"), the raw-file loop does not stop. If the file contains at least one more byte, the next loop iteration appends a new chunk to an object that is already invalid. With assertions enabled this aborts in jvp_string_ptr(). With assertions disabled, the invalid object is interpreted as a string object and ASan reports heap-buffer-overflow. This vulnerability is fixed in 1.8.2.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H.
EPSS exploit prediction
EPSS: 0.002 (5.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 5.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.000
Affected products
- Jqlang Jq — versions < 1.8.2
Weakness classification (CWE)
References
- github.com/jqlang/jq/security/advisories/GHSA-cfh2-vwfq-qfmm (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-49839?
- CVE-2026-49839 is a high-severity vulnerability in Jqlang Jq, classified under Out-of-bounds Write. CVSS score: 7.1/10. Published 2026-06-25.
- How severe is CVE-2026-49839?
- High severity. CVSS v3 base score is 7.1 out of 10.