Home/CVE/PuTTY before 0.75 on Windows allows remote servers to cause a denial of service (Windows GUI hang) by telling the PuTTY
CVE

CVE-2021-33500

PuTTY before 0.75 on Windows allows remote servers to cause a denial of service (Windows GUI hang) by telling the PuTTY

PuTTY before 0.75 on Windows allows remote servers to cause a denial of service (Windows GUI hang) by telling the PuTTY window to change its title repeatedly at high speed, which results in many SetWindowTextA or SetWindowTextW calls. NOTE: the same attack methodology may affect some OS-level GUIs on Linux or other platforms for similar reasons.

HIGH · CVSS 7.5 EPSS 0.004
Act now
  • Public exploit or PoC is available
  • CVSS base score ≥ 7.0
Sigma rules7 YARA rules0
▤

Affected Products & Versions

1
putty< 0.75
⚠

Public Exploits & PoCs

2
pocdocs.ssh-mitm.at · puttydos.htmldocs.ssh-mitm.at
pocgithub.com · putty_dos.pygithub.com
◈

Sigma Hunt Rules

7
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productcriticalHackTool - Windows Credential Editor (WCE) Execution
productcriticalWindows Credential Editor Registry
producthighOpenCanary - MSSQL Login Attempt Via Windows Authentication
producthighWindows LAPS Credential Dump From Entra ID
producthighTamper Windows Defender - PSClassic
producthighTamper Windows Defender Remove-MpPreference - ScriptBlockLogging
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD21 May 2021 · 08:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.htmlRelease NotesThird Party Advisory
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