Vulnerability in MessagePack (CVE-2026-48506)
Summary
Vulnerability in MessagePack (CVE-2026-48506). Risk of unauthorized operations or information disclosure. Exploitable via StackOverflowException. Mitigation: upgrade to 3.1.7 or later.
Original description
The description as published by the source.
Summary
MessagePackReader.TrySkip() recursively descends into nested arrays and maps without incrementing the reader depth or calling the configured depth checks. This bypasses MessagePackSecurity.MaximumObjectGraphDepth, the library's documented protection against deeply nested object graphs.
Many generated and dynamic formatters call reader.Skip() when they encounter unknown map keys, unknown array members, ignored fields, or data that should be skipped for forward compatibility. A deeply nested value in one of these skipped positions can therefore cause unbounded recursion and an uncatchable StackOverflowException.
Impact
Applications that deserialize untrusted MessagePack payloads are affected when a formatter skips attacker-controlled values. This is a broad deserialization path and can be reached during normal object deserialization when an input includes an unknown member or extra value.
The attacker does not need to target a special resolver or compression mode. A payload containing many nested single-element arrays or maps in a skipped location can exhaust the process stack. Because StackOverflowException is not catchable in normal .NET execution, this terminates the host process and can deny service to other users of the same process.
MessagePackSecurity.UntrustedData does not mitigate this issue because the skip path does not participate in depth accounting.
Affected components
- Package:
MessagePack - APIs:
MessagePackReader.Skip,…
Source: NIST National Vulnerability Database 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-2026-48506 has been found in MessagePack.
Attackers can target a specific entry point like StackOverflowException over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade MessagePack to 3.1.7 or later.
If unsure, ask your IT team or search "MessagePack CVE-2026-48506" on the vendor's site.
CVE-2026-48506 (MessagePack) — CWE-674 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: StackOverflowException / MessagePackSecurity.UntrustedData / MessagePack / MessagePackReader.Skip
Patched: 3.1.7 — 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.
A vulnerability (CWE-674) exists in MessagePack. Attackers reach the vulnerable code path via StackOverflowException without authentication.
Check the vendor advisory for the affected versions of MessagePack. Attack surface: StackOverflowException / MessagePackSecurity.UntrustedData / MessagePack / MessagePackReader.Skip.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 3.1.7.
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 'MessagePack' . 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
-
1Identify exposure identify
grep -r 'MessagePack' . | 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
MessagePack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 MessagePack to 3.1.7ステージング環境で 3.1.7 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。
-
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。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com