CVE-2018-25221Public exploitNetwork attack vector

Unauthenticated code execution via oversized username

Published Mar 28, 2026 · Updated Mar 28, 2026

Out-of-bounds write in Easy Chat Server 3.1 allows remote attackers to execute arbitrary code through an oversized chat.ghp username. The endpoint places roughly 2,775 crafted bytes into an undersized buffer, overwriting exception-handler control data before reaching embedded shellcode. An unauthenticated GET request is sufficient; successful exploitation runs code in the application context, while failed attempts can crash the server.

CVSS severity9.3
Critical
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Easy Chat Server 3.1 allows remote attackers to execute arbitrary code through an oversized chat.ghp username. The endpoint places roughly 2,775 crafted bytes into an undersized buffer, overwriting exception-handler control data before reaching embedded shellcode. An unauthenticated GET request is sufficient; successful exploitation runs code in the application context, while failed attempts can crash the server.

The record

CVE
CVE-2018-25221
Published
Mar 28, 2026
Updated
Mar 28, 2026
Vendor
EFS Software, Inc.
Product
Easy Chat Server
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 28, 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=3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

EFS Software, Inc. · Easy Chat Serverversion=3.1

Published CVSS scores

9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

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

Technologies

Your stack

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Your stack

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