CVE-2021-33500

Exploitation

Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.

SSVC decision

Not assessed by CISA

EPSS probability

1.97% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 78.6% of scored records. A rank, not a probability.

NVD base score

7.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-05-21 19:42Z5 YR AGO

Last updated

2024-08-03 23:50Z2 YR AGO

Reserved

2021-05-21

Assigning CNA

mitre

Record state

PUBLISHED

Severity

High (CVSS 7.5)

CNA CVSS vector

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

Weaknesses

No CWE assigned

Data version

5.1

Document digest

26ec81be37f0e90912039595083bc28cc2fa446e16f9ab9d3ca69ace99cff3ae

• www.chiark.greenend.org.ukhttps://www.chiark.greenend.org.uk/~sgtatham/putty/changes.htmlx_refsource_MISC
• docs.ssh-mitm.athttps://docs.ssh-mitm.at/puttydos.htmlx_refsource_MISC
• github.comhttps://github.com/ssh-mitm/ssh-mitm-plugins/blob/main/ssh_mitm_plugins/ssh/putty_dos.pyx_refsource_MISC