CVE-2026-48512Network attack vector

Process crash via unbounded JSON conversion recursion

Published Jun 22, 2026 · Updated Jun 22, 2026

Uncontrolled recursion in MessagePack for C# before 2.5.301 and 3.0 through 3.1.6 allows remote attackers to crash consuming processes. ConvertFromJson omits object-graph depth checks, TinyJsonReader self-recurses on separators, and ext-100 conversion skips DepthStep. Exposure requires an application to pass attacker-controlled JSON or typeless MessagePack to these APIs; stack exhaustion raises an uncatchable StackOverflowException.

CVSS severity6.3
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in MessagePack for C# before 2.5.301 and 3.0 through 3.1.6 allows remote attackers to crash consuming processes. ConvertFromJson omits object-graph depth checks, TinyJsonReader self-recurses on separators, and ext-100 conversion skips DepthStep. Exposure requires an application to pass attacker-controlled JSON or typeless MessagePack to these APIs; stack exhaustion raises an uncatchable StackOverflowException.

The record

CVE
CVE-2026-48512
Published
Jun 22, 2026
Updated
Jun 22, 2026
Vendor
MessagePack-CSharp
Product
MessagePack for C#
Classifications
CWE-674, 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

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.3GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

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-674Uncontrolled Recursion
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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