CVE-2026-48510Network attack vectorHinoki check available

Process termination via unbounded LZ4 output allocation

Published Jun 22, 2026 · Updated Jun 22, 2026

Denial of service in MessagePack for C# before 2.5.301 and 3.0 through 3.1.6 allows remote attackers to terminate processes. MessagePackSerializer.TryDecompress trusts Lz4Block or Lz4BlockArray output lengths from the payload and allocates destination buffers before validating compressed data or bounding total expansion. Reachability requires attacker-controlled MessagePack data and an application configured for either built-in LZ4 mode; repeated oversized declarations exhaust memory or terminate the consuming process.

CVSS severity6.3
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in MessagePack for C# before 2.5.301 and 3.0 through 3.1.6 allows remote attackers to terminate processes. MessagePackSerializer.TryDecompress trusts Lz4Block or Lz4BlockArray output lengths from the payload and allocates destination buffers before validating compressed data or bounding total expansion. Reachability requires attacker-controlled MessagePack data and an application configured for either built-in LZ4 mode; repeated oversized declarations exhaust memory or terminate the consuming process.

The record

CVE
CVE-2026-48510
Published
Jun 22, 2026
Updated
Jun 22, 2026
Vendor
MessagePack-CSharp
Product
MessagePack for C#
Classifications
CWE-770, CWE-409, T1499
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

Compare your product and version with the public record. A matching version still requires validation against your environment.

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

6.3GitHubCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-770Allocation of Resources Without Limits or Throttling
CWE-409Improper Handling of Highly Compressed Data (Data Amplification)
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo