Vulnerability in msgpack5 (CVE-2026-107296)
Summary
Vulnerability in msgpack5 (CVE-2026-107296). 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
Decoding a negative signed 64-bit integer modifies the corresponding bytes in the caller-provided input buffer. Applications that retain or reuse encoded input for integrity checks, logging, or subsequent processing may observe silently corrupted data.
Positive integers and other MessagePack value types are not affected.
Patches
The decoder now computes signed 64-bit values without writing to the input buffer.
Workarounds
Copy untrusted MessagePack input before decoding it, or do not retain or reuse input buffers after decoding.
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-2026-107296 has been found in msgpack5.
Risk of unauthorized operations or information disclosure. CVSS score: 3.7/10.
What to do: upgrade msgpack5 to 6.1.0 or later.
If unsure, ask your IT team or search "msgpack5 CVE-2026-107296" on the vendor's site.
CVE-2026-107296 (msgpack5) — CWE-471 / CVSS v3 3.7
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 6.1.0 — apply immediately
Workaround: Copy untrusted MessagePack input before decoding it, or do not retain or reuse input buffers after decoding.
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-471) exists in msgpack5.
Check the vendor advisory for the affected versions of msgpack5.
Severity: Low (CVSS 3.7/10). Risk of unauthorized operations or information disclosure.
Update to 6.1.0.
Workaround: Copy untrusted MessagePack input before decoding it, or do not retain or reuse input buffers after decoding.
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
Copy untrusted MessagePack input before decoding it, or do not retain or reuse input buffers after decoding.パッチが適用されるまでの応急処置として、Copy untrusted MessagePack input before decoding it, or do not retain or reuse input buffers after decoding. 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。