PuTTY before 0.73 might allow remote SSH-1 servers to cause a denial of service by accessing freed memory locations via an SSH1_MSG_DISCONNECT message.
Weakness
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Putty | Putty | * | 0.73 (excluding) |
| Putty | Ubuntu | bionic | * |
| Putty | Ubuntu | disco | * |
| Putty | Ubuntu | eoan | * |
| Putty | Ubuntu | trusty | * |
| Putty | Ubuntu | upstream | * |
| Putty | Ubuntu | xenial | * |
Potential Mitigations
References
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00020.html
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00021.html
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00030.html
- https://lists.debian.org/debian-lts-announce/2024/04/msg00016.html
- https://lists.tartarus.org/pipermail/putty-announce/2019/000029.html
- https://security.netapp.com/advisory/ntap-20191127-0003/
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00020.html
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00021.html
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00030.html
- https://lists.debian.org/debian-lts-announce/2024/04/msg00016.html
- https://lists.tartarus.org/pipermail/putty-announce/2019/000029.html
- https://security.netapp.com/advisory/ntap-20191127-0003/