MessagePack-CSharp: Denial of service vulnerabilities can swamp the CPU or crash the process with stack and heap overflows
Summary
| CVE | CVE-2026-48502 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-06-22 22:16:47 UTC |
| Updated | 2026-06-23 17:25:05 UTC |
| Description | MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePackReader.ReadDateTime() can allocate stack memory based on an attacker-controlled MessagePack extension length. In the slow path for timestamp extension parsing, the computed tokenSize includes the extension body length from the wire and is used in a stackalloc operation before the extension length is validated as one of the valid timestamp sizes. A very small payload can claim a large timestamp extension body and cause a stack allocation large enough to trigger an uncatchable StackOverflowException, terminating the host process. This vulnerability is fixed in 2.5.301 and 3.1.7. |
Risk And Classification
Primary CVSS: v4.0 8.2 HIGH from [email protected]
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.002450000 probability, percentile 0.153830000 (date 2026-06-23)
Problem Types: CWE-125 | CWE-190 | CWE-407 | CWE-409 | CWE-470 | CWE-502 | CWE-674 | CWE-789 | CWE-1188 | CWE-125 CWE-125: Out-of-bounds Read | CWE-190 CWE-190: Integer Overflow or Wraparound | CWE-407 CWE-407: Inefficient Algorithmic Complexity | CWE-409 CWE-409: Improper Handling of Highly Compressed Data (Data Amplification) | CWE-470 CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') | CWE-502 CWE-502: Deserialization of Untrusted Data | CWE-674 CWE-674: Uncontrolled Recursion | CWE-789 CWE-789: Memory Allocation with Excessive Size Value | CWE-1188 CWE-1188: Insecure Default Initialization of Resource
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 8.2 | HIGH | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | DECLARED | 8.2 | HIGH | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| 3.1 | [email protected] | Primary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Messagepack | Messagepack | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | MessagePack-CSharp | MessagePack-CSharp | affected >= 3.1.7, < 3.1.7 | Not specified |
| CNA | MessagePack-CSharp | MessagePack-CSharp | affected < 2.5.301 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHS... | [email protected] | github.com | Mitigation, Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |