CVE-2021-33500

HIGH
Published May 21, 20215y ago · Modified Jun 17, 20261w ago
7.5 CVSS 3.1
High
Find Similar
Published May 21, 2021 5y ago
Last Modified Jun 17, 2026 1w ago

Description

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.

CVSS Details

Base Score
7.5
Exploitability
3.9
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

No active exploitation signals — not in CISA KEV and no EPSS score yet.

Exploit & Patch Status
Public Exploit Known
No Patch Available

Affected Products 2

VendorProductVersionRange
puttyputty* <0.75
microsoftwindows*any

References 3

  • docs.ssh-mitm.at https://docs.ssh-mitm.at/puttydos.html
    ExploitThird Party Advisory
  • github.com https://github.com/ssh-mitm/ssh-mitm-plugins/blob/main/ssh_mitm_plugins/ssh/putty_dos.py
    ExploitThird Party Advisory
  • chiark.greenend.org.uk https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.html
    Release NotesThird Party Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.