CVE-2021-32795Public exploitNetwork attack vector

Service crash via prefix-only Steam chat message

Published Jul 26, 2021 · Updated Aug 3, 2024

Improper input validation in JustArchiNET ArchiSteamFarm before 4.3.1.0 allows remote attackers to crash the service via Steam chat. Commands.HandleMessage strips the configured prefix from a prefix-only message, passes an empty command to Response, and triggers an unhandled ArgumentNullException. Any Steam user who knows the CommandPrefix can terminate the running process; the common default prefix lowers that gate, while offline bots do not parse the message.

CVSS severity6.5
Medium
EPSS probability1.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in JustArchiNET ArchiSteamFarm before 4.3.1.0 allows remote attackers to crash the service via Steam chat. Commands.HandleMessage strips the configured prefix from a prefix-only message, passes an empty command to Response, and triggers an unhandled ArgumentNullException. Any Steam user who knows the CommandPrefix can terminate the running process; the common default prefix lowers that gate, while offline bots do not parse the message.

The record

CVE
CVE-2021-32795
Published
Jul 26, 2021
Updated
Aug 3, 2024
Vendor
JustArchiNET
Product
ArchiSteamFarm
Classifications
CWE-20, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=>= 4.3.0.0, < 4.3.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

JustArchiNET · ArchiSteamFarmversion=>= 4.3.0.0, < 4.3.1.0

Published CVSS scores

5.9NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
4.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:N/I:N/A:P
6.5GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/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 exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499Endpoint Denial of Service

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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