CVE-2026-48109

HIGH EPSS 21.3%
Published Jun 22, 20261w ago · Modified Jun 23, 20261w ago
8.2 CVSS 3.1
High
Find Similar
Published Jun 22, 2026 1w ago
Last Modified Jun 23, 2026 1w ago

Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, A vulnerability exists in the optional LZ4 decompression path used by MessagePack compression modes Lz4Block and Lz4BlockArray. The decoder implementation is based on a deprecated fast-decompression algorithm that does not take a source-length bound. A remote attacker can send a crafted MessagePack payload with manipulated LZ4 token/length fields to force out-of-bounds reads from the compressed input buffer. In affected environments, this can trigger an AccessViolationException during decompression, causing process termination (denial of service). Under some conditions, limited unintended memory disclosure from over-read data may also be possible before failure. This vulnerability is fixed in 2.5.301 and 3.1.7.

CVSS Details

Base Score
8.2
Exploitability
3.9
Impact
4.2
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Low
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
21.3% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-20 Improper Input Validation Validation

Affected Products 2

VendorProductVersionRange
messagepackmessagepack* <2.5.301
messagepackmessagepack*≥3.0.3  –  <3.1.7

References 1

  • github.com https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-hv8m-jj95-wg3x
    MitigationVendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.