CVE-2026-48514

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, UnsafeBlitFormatterBase<T>.Deserialize reads an attacker-controlled byteLength from an extension payload and allocates an array based on that value before validating it against the extension header length or remaining payload bytes. The outer extension header is bounded by available input, but that bound is not used to constrain the inner byteLength before allocation. A very small payload can therefore request a very large T[] allocation. This vulnerability is fixed in 2.5.301 and 3.1.7.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-w567-gjr2-hm5j	Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:messagepack:messagepack::::::c\#::*
	cpe:2.3:a:messagepack:messagepack::::::c\#::*

History

23 Jun 2026, 17:20

Type	Values Removed	Values Added
CPE		cpe:2.3:a:messagepack:messagepack::::::c\#::*
First Time		Messagepack messagepack Messagepack
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 7.5
References	~~() https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-w567-gjr2-hm5j -~~	() https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-w567-gjr2-hm5j - Mitigation, Vendor Advisory

22 Jun 2026, 22:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-22 22:16

Updated : 2026-06-25 16:16

NVD link : CVE-2026-48514

Mitre link : CVE-2026-48514

CVE.ORG link : CVE-2026-48514

JSON object : View

Products Affected

messagepack

messagepack

CWE

CWE-770

Allocation of Resources Without Limits or Throttling

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