Description
Integer overflow in PuTTY 0.62 and earlier, WinSCP before 5.1.6, and other products that use PuTTY allows remote SSH servers to cause a denial of service (crash) and possibly execute arbitrary code in certain applications that use PuTTY via a negative size value in an RSA key signature during the SSH handshake, which triggers a heap-based buffer overflow.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | filezilla | 3.7.3-1 | — |
| Debian 14 | putty | 0.63-1 | — |
| Debian 13 | filezilla | 3.7.3-1 | — |
| Debian 13 | putty | 0.63-1 | — |
| Debian 12 | filezilla | 3.7.3-1 | — |
| Debian 12 | putty | 0.63-1 | — |
| Debian 7 | putty | 0.62-9+deb7u1 | DSA-2736-1 |
| Debian 6.0 | putty | 0.60+2010-02-20-1+squeeze2 | DSA-2736-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | putty | 0.63-1 | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | filezilla | 3.23.0.2-1.1 | openSUSE-SU-2024:10399-1 |
| openSUSE Tumbleweed | putty | 0.67-1.5 | openSUSE-SU-2024:10374-1 |
Advisories 3
- DSA-2736-1 putty - several Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10399-1 filezilla-3.23.0.2-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10374-1 putty-0.67-1.5 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- 54533 third-party-advisory
- 54517 third-party-advisory
- http://winscp.net/tracker/show_bug.cgi?id=1017
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718779
- http://www.search-lab.hu/advisories/secadv-20130722
- DSA-2736 vendor-advisory
- http://svn.tartarus.org/sgt?view=revision&sortby=date&revision=9896
- openSUSE-SU-2013:1347 vendor-advisory
- 54379 third-party-advisory
- http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-signature-stringlen.html
- openSUSE-SU-2013:1355 vendor-advisory