CVE-2021-33500

HighCVSS 7.5/10Last modified Jun 17, 2026

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.

Metrics

CVSS 3.1 7.5/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected software

Vendor	Product	Versions
n/a	n/a	n/a

References

https://docs.ssh-mitm.at/puttydos.htmlExploit, Third Party Advisory
https://github.com/ssh-mitm/ssh-mitm-plugins/blob/main/ssh_mitm_plugins/ssh/putty_dos.pyExploit, Third Party Advisory
https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.htmlRelease Notes, Third Party Advisory
https://docs.ssh-mitm.at/puttydos.htmlExploit, Third Party Advisory
https://github.com/ssh-mitm/ssh-mitm-plugins/blob/main/ssh_mitm_plugins/ssh/putty_dos.pyExploit, Third Party Advisory
https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.htmlRelease Notes, Third Party Advisory

Timeline

Published: May 21, 2021
Last modified: Jun 17, 2026
NVD status: Modified

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