What is CVE-2026-48109?

CVE-2026-48109 is a high-severity vulnerability in Messagepack, classified under Improper Input Validation. CVSS score: 8.2/10. Published 2026-06-22.

How severe is CVE-2026-48109?

High severity. CVSS v3 base score is 8.2 out of 10.

Improper input validation in Messagepack

CVE-2026-48109

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 i…

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H.

Affected products

Messagepack
Messagepack-csharp — versions >= 3.1.7, < 3.1.7, < 2.5.301

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-48109?: CVE-2026-48109 is a high-severity vulnerability in Messagepack, classified under Improper Input Validation. CVSS score: 8.2/10. Published 2026-06-22.
How severe is CVE-2026-48109?: High severity. CVSS v3 base score is 8.2 out of 10.