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CVE-2021-36367PuTTY through 0.75 proceeds with establishing an SSH session even if it has never sent a substantive authentication response. This makes…
- 8.1HighCVSS base score
- 1.1%Exploitation in 30 daysEPSS · top 34% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
PuTTY through 0.75 proceeds with establishing an SSH session even if it has never sent a substantive authentication response. This makes it easier for an attacker-controlled SSH server to present a later spoofed authentication prompt (that the attacker can use to capture credential data, and use that data for purposes that are undesired by the client user).
Timeline
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | High8.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N |
| NVDNVD · Modified | 3.1 | High8.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N |
- EPSS (exploitation in 30 days)
- 1.1% · top 34% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.1.
Affected products
n/a
- affected n/a
References
References4
- https://www.chiark.greenend.org.uk/~sgtatham/putty/changes.html (opens in a new tab)x_transferred
- https://git.tartarus.org/?p=simon/putty.git%3Ba=commit%3Bh=1dc5659aa62848f0aeb5de7bd3839fecc7debefa (opens in a new tab)x_transferred
- DSA-5588 (opens in a new tab)vendor-advisoryx_transferred
- [debian-lts-announce] 20240425 [SECURITY] [DLA 3794-1] putty security update (opens in a new tab)mailing-listx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-22987 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-36367)Record last updated .