Corrective releases of the Tor toolkit (0.3.5.14, 0.4.4.8, 0.4.5.7), used to organize the operation of the Tor anonymous network, are presented. The new versions eliminate two vulnerabilities that can be used to carry out DoS attacks on Tor network nodes:
- CVE-2021-28089 - an attacker can cause a denial of service to any Tor nodes and clients by creating a large CPU load that occurs when processing certain types of data. The vulnerability is most dangerous for relays and Directory Authority servers, which are connection points to the network and are responsible for authenticating and transmitting to the user a list of gateways that process traffic. Directory servers are the easiest to attack because they allow anyone to upload data. An attack against relays and clients can be organized by downloading the directory cache.
- CVE-2021-28090 - an attacker can cause a directory server to crash by transmitting a specially designed detached signature, which is used to convey information about the state of consensus on the network.
Source: opennet.ru