TigerVNC version prior to 1.10.1 is vulnerable to stack use-after-return, which occurs due to incorrect usage of stack memory in ZRLEDecoder. If decoding routine would throw an exception, ZRLEDecoder may try to access stack variable, which has been already freed during the process of stack unwinding. Exploitation of this vulnerability could potentially result into remote code execution. This attack appear to be exploitable via network connectivity.
Weakness
The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Tigervnc | Tigervnc | * | 1.10.1 (excluding) |
| Red Hat Enterprise Linux 7 | RedHat | tigervnc-0:1.8.0-21.el7 | * |
| Red Hat Enterprise Linux 8 | RedHat | tigervnc-0:1.9.0-14.el8_1 | * |
| Tigervnc | Ubuntu | bionic | * |
| Tigervnc | Ubuntu | disco | * |
| Tigervnc | Ubuntu | eoan | * |
| Tigervnc | Ubuntu | trusty | * |
| Tigervnc | Ubuntu | upstream | * |
Potential Mitigations
References
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00039.html
- https://github.com/CendioOssman/tigervnc/commit/d61a767d6842b530ffb532ddd5a3d233119aad40
- https://github.com/TigerVNC/tigervnc/releases/tag/v1.10.1
- https://www.openwall.com/lists/oss-security/2019/12/20/2
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00039.html
- https://github.com/CendioOssman/tigervnc/commit/d61a767d6842b530ffb532ddd5a3d233119aad40
- https://github.com/TigerVNC/tigervnc/releases/tag/v1.10.1
- https://www.openwall.com/lists/oss-security/2019/12/20/2