DescriptionPuTTY 0.68 through 0.73 has an Observable Discrepancy leading to an information leak in the algorithm negotiation. This allows man-in-the-middle attackers to target initial connection attempts (where no host key for the server has been cached by the client).
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
putty (PTS)stretch (security), stretch0.67-3+deb9u1vulnerable
bullseye, sid0.74-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs


[buster] - putty <no-dsa> (Minor issue)
[stretch] - putty <no-dsa> (Minor issue)
[jessie] - putty <no-dsa> (Minor issue)
Fixed by:;a=commit;h=08f1e2a5066ea95559945af339a60ca14560d764 (0.74)

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