Out-of-Bounds Write in jq (CVE-2026-49839)
Summary
Out-of-bounds write in jq (CVE-2026-49839). Data can be tampered with by attackers. Mitigation: upgrade to 1.8.2 or later.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49839 has been found in jq.
Data can be tampered with by attackers. CVSS score: 7.1/10.
What to do: upgrade jq to 1.8.2 or later.
If unsure, ask your IT team or search "jq CVE-2026-49839" on the vendor's site.
CVE-2026-49839 (jq) — CWE-787 / CVSS v3 7.1
Attack vector: local / unauthenticated
Patched: 1.8.2 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Out-of-bounds write (CWE-787) exists in jq.
Check the vendor advisory for the affected versions of jq.
Severity: High (CVSS 7.1/10). Data can be tampered with by attackers.
Update to 1.8.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'jq' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'jq' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
jqを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade jq to 1.8.2ステージング環境で 1.8.2 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-49839 jq Fixed in: 1.8.2-r0
- Debian DEBIAN-CVE-2026-49839 jq
- Ubuntu UBUNTU-CVE-2026-49839 jq
References
- exploit github.com