What is CVE-2026-48511?

CVE-2026-48511 is a high-severity vulnerability in Messagepack, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-06-22.

How severe is CVE-2026-48511?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Messagepack

CVE-2026-48511

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, ExpandoObjectFormatter.Deserialize populates System.Dynamic.ExpandoObject by calling IDictionary<string, object>.Add for each map entry. ExpandoObject inter…

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

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

Weakness classification (CWE)

CWE-407 — Inefficient Algorithmic Complexity

References

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

Frequently asked questions

What is CVE-2026-48511?: CVE-2026-48511 is a high-severity vulnerability in Messagepack, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-06-22.
How severe is CVE-2026-48511?: High severity. CVSS v3 base score is 7.5 out of 10.