CVE-2026-48502Network attack vectorHinoki check available

Process termination via oversized timestamp extension length

Published Jun 22, 2026 · Updated Jun 22, 2026

Denial of service in MessagePack for C# before 2.5.301 and 3.0.0 through 3.1.6 allows remote attackers to terminate host processes. In MessagePackReader.ReadDateTime(), tokenSize incorporates the untrusted extension body length and drives stackalloc before timestamp-size validation. Any application that deserializes untrusted MessagePack data into DateTime-bearing types can suffer an uncatchable StackOverflowException and process termination.

CVSS severity8.2
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
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Summary

What happened

Denial of service in MessagePack for C# before 2.5.301 and 3.0.0 through 3.1.6 allows remote attackers to terminate host processes. In MessagePackReader.ReadDateTime(), tokenSize incorporates the untrusted extension body length and drives stackalloc before timestamp-size validation. Any application that deserializes untrusted MessagePack data into DateTime-bearing types can suffer an uncatchable StackOverflowException and process termination.

The record

CVE
CVE-2026-48502
Published
Jun 22, 2026
Updated
Jun 22, 2026
Vendor
MessagePack-CSharp
Product
MessagePack for C#
Classifications
CWE-789, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.5.301
  2. Affected versionversion=>= 3.1.7, < 3.1.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MessagePack-CSharp · MessagePack for C#version=< 2.5.301; version=>= 3.1.7, < 3.1.7

Published CVSS scores

8.2GitHub, Inc.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
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-789Memory Allocation with Excessive Size Value
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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