Under certain conditions, named may crash when processing a correctly signed query containing a TKEY record. The affected code can only be reached if an incoming request has a valid transaction signature (TSIG) from a key declared in the named configuration.
This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1.
BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.
Weakness
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Bind | Isc | 9.20.0 (including) | 9.20.21 (excluding) |
| Bind | Isc | 9.21.0 (including) | 9.21.20 (excluding) |
| Red Hat Hardened Images | RedHat | bind-main-9.18.48-1.hum1 | * |
| Bind9 | Ubuntu | questing | * |
| Bind9 | Ubuntu | upstream | * |
| Isc-dhcp | Ubuntu | questing | * |
Extended Description
While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.