CVE-2022-21716Public exploitNetwork attack vector

Unauthenticated service crash via unbounded SSH identifier buffering

Published Mar 3, 2022 · Updated Apr 22, 2025

Resource exhaustion in Twisted before 22.2.0 allows remote attackers to crash SSH clients or servers with an unterminated version identifier. SSHTransportBase.dataReceived repeatedly appends peer-controlled bytes to self.buf while waiting for a newline and, before the patch, enforces no size limit. No authentication or user interaction is required; an SSH client or server that accepts a malicious peer can exhaust process memory and crash.

CVSS severity7.5
High
EPSS probability3.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Resource exhaustion in Twisted before 22.2.0 allows remote attackers to crash SSH clients or servers with an unterminated version identifier. SSHTransportBase.dataReceived repeatedly appends peer-controlled bytes to self.buf while waiting for a newline and, before the patch, enforces no size limit. No authentication or user interaction is required; an SSH client or server that accepts a malicious peer can exhaust process memory and crash.

The record

CVE
CVE-2022-21716
Published
Mar 3, 2022
Updated
Apr 22, 2025
Vendor
Twisted
Product
Twisted
Classifications
CWE-770, CWE-120, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 3, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2025Record 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=< 22.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Twisted · Twistedversion=< 22.2.0

Published CVSS scores

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 exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

Public exploit references

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