Vulnerability in msgpack5 (CVE-2026-107300)
Summary
Vulnerability in msgpack5 (CVE-2026-107300). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.1.0 or later.
Original description
The description as published by the source.
Impact
The streaming decoder recursively invokes itself for every complete value remaining in a chunk. A single chunk containing many small valid MessagePack values can exhaust the JavaScript call stack and interrupt the process or stream.
Patches
The streaming decoder now drains concatenated values iteratively with constant call-stack depth.
Workarounds
Limit the number of MessagePack values accepted in one chunk, or split large batches before passing them to the decoder stream.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
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-2026-107300 has been found in msgpack5.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade msgpack5 to 6.1.0 or later.
If unsure, ask your IT team or search "msgpack5 CVE-2026-107300" on the vendor's site.
CVE-2026-107300 (msgpack5) — CWE-674 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 6.1.0 — apply immediately
Workaround: Limit the number of MessagePack values accepted in one chunk, or split large batches before passing them to the decoder stream.
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.
A vulnerability (CWE-674) exists in msgpack5.
Check the vendor advisory for the affected versions of msgpack5.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 6.1.0.
Workaround: Limit the number of MessagePack values accepted in one chunk, or split large batches before passing them to the decoder stream.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'msgpack5' . 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 'msgpack5' . | 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
msgpack5を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
Limit the number of MessagePack values accepted in one chunk, or split large batches before passing them to the decoder stream.パッチが適用されるまでの応急処置として、Limit the number of MessagePack values accepted in one chunk, or split large batches before passing them to the decoder stream. を実施。回避策の副作用 (機能低下) を確認した上で。
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3Apply patch patch
Upgrade msgpack5 to 6.1.0ステージング環境で 6.1.0 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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4Post-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。
Affected packages
References
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com