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TI-2021-12902 Aliases CVE-2021-33500GHSA-vmq2-m9cv-qwqx

PuTTY before 0.75 on Windows allows remote servers to cause a denial of service (Windows…

Priority LOW 37Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

EPSS 0.01914 79th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:putty:putty:*:*:*:*:*:*:*:*before 0.75VulnerablePuTTY
cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*not specified by NVDRunning onMicrosoft
  • cpe:2.3:a:putty:putty:*:*:*:*:*:*:*:* Versions before 0.75 Vulnerable ·PuTTY
  • cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Microsoft

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-33500
  2. 2026-10-03 Alias added: GHSA-vmq2-m9cv-qwqx

References

Exploit 2

Advisory 1

  • TI-2002-01283 Multiple SSH2 servers and clients do not properly handle large packets or large fields… CVSS 2.0HIGH 10.0
  • TI-2023-26623 The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6… CVSS 3.1MEDIUM 5.9
  • TI-2017-04321 The ssh_agent_channel_data function in PuTTY before 0.68 allows remote attackers to have… CVSS 3.0CRITICAL 9.8
  • TI-2026-03565 PuTTY Ed25519 Signature ecc-ssh.c eddsa_verify signature verification CVSS 4.0MEDIUM 6.3
  • TI-2002-01281 Multiple SSH2 servers and clients do not properly handle packets or data elements with… CVSS 2.0HIGH 10.0
  • TI-2004-00914 Integer signedness error in the ssh2_rdpkt function in PuTTY before 0.56 allows remote… CVSS 2.0HIGH 10.0
See all 35 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences