MessagePack Known Vulnerabilities & Fixes
MessagePack has 7 known security vulnerabilities in NuGet (.NET). Upgrade to version 3.1.7 or later to resolve all known issues. Data sourced from OSV, enriched with EPSS exploit probability and CISA KEV.
Low Immediate Risk
No actively exploited vulnerabilities detected. Monitor and update in your next maintenance window.
Recommended safe version: 3.1.7
Upgrading to 3.1.7 or later resolves all 7 known vulnerabilities in MessagePack. Run: dotnet add package MessagePack --version 3.1.7
Is MessagePack in your project?
Check if you're affected and upgrade to 3.1.7 to stay secure.
Security Summary
- 13 affected version ranges have been identified across these 7 advisories.
- 100% of known issues have a published fixed version.
- Remediation: dotnet add package MessagePack
Vulnerabilities
7 unique vulnerabilities — sorted by exploitation risk (KEV → EPSS → CVSS). Click a CVE/GHSA ID for full details. First disclosed Jan 31, 2020, most recently Jun 25, 2026 (2337 days apart).
| CVE / GHSA | Severity | Affected | Fixed In |
|---|---|---|---|
| CVE-2026-48502 MessagePack-CSharp: Denial of service vulnerabilities can swamp the CPU or crash the process with stack and heap overflows | HIGH | 3.0.111-alpha, 3.0.129-beta, 3.0.134-beta, 3.0.208-rc-0001 (+11 more) | 3.1.7 |
| CVE-2026-48109 MessagePack's LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad input | HIGH | 0.1.0-beta, 0.2.0-beta, 0.2.1-beta, 0.2.2-beta (+125 more) | 2.5.301, 3.1.7 |
| CVE-2026-48506 MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depth | HIGH | 0.1.0-beta, 0.2.0-beta, 0.2.1-beta, 0.2.2-beta (+131 more) | 2.5.301, 3.1.7 |
| CVE-2020-5234 Untrusted data can lead to DoS attack due to hash collisions and stack overflow in MessagePack | MEDIUM | 0.1.0-beta, 0.2.0-beta, 0.2.1-beta, 0.2.2-beta (+81 more) | 1.9.11, 2.1.90 |
| CVE-2026-48509 MessagePack-CSharp: ASP.NET Core MessagePackInputFormatter defaults to TrustedData for HTTP request bodies | MEDIUM | 0.1.0-beta, 0.2.0-beta, 0.2.1-beta, 0.2.2-beta (+131 more) | 2.5.301, 3.1.7 |
| CVE-2026-48511 MessagePack-CSharp: ExpandoObject formatter can perform quadratic insertion work on untrusted maps | MEDIUM | 0.1.0-beta, 0.2.0-beta, 0.2.1-beta, 0.2.2-beta (+131 more) | 2.5.301, 3.1.7 |
| CVE-2026-48510 MessagePack-CSharp: LZ4 decompression allocates from unbounded declared output lengths | MEDIUM | 0.1.0-beta, 0.2.0-beta, 0.2.1-beta, 0.2.2-beta (+131 more) | 2.5.301, 3.1.7 |
About This Data
Vulnerability data for MessagePack is sourced from the Open Source Vulnerability (OSV) database, aggregating reports from GitHub Advisory Database, NIST NVD, and ecosystem-specific sources.
CVSS (Common Vulnerability Scoring System) scores reflect exploitability and impact. EPSS (Exploit Prediction Scoring System) scores indicate the probability of exploitation within the next 30 days. Vulnerabilities marked with are listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.
Related NuGet (.NET) Packages
Other packages in this ecosystem, ranked by shared vulnerabilities where available.
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