In Tor, 800 out of 6000 nodes have been disabled due to the use of outdated software.

Developers of the anonymous network Tor warned about a major cleanup of nodes running outdated software that is no longer supported. On October 8, about 800 outdated nodes operating in relay mode were blocked (there are more than 6000 such nodes in the Tor network). The blocking was carried out by placing problematic nodes on a blacklist in the directory servers. The exclusion of outdated bridge nodes from the network is expected to occur later.

In the next stable release of Tor, scheduled for November, there will be an option that by default rejects connections to nodes
running versions of Tor that have reached their end of life. Such a change will allow for the automatic exclusion of nodes from the network that have not transitioned to the current software in accordance with the support cessation of upcoming branches. For example, nodes using Tor 0.2.4.x, which was released in 2013, can still be found in the Tor network, despite the fact that support for the LTS branch 0.2.9 is still ongoing. Operators of outdated systems were notified of the planned blocking in

September via mailing lists and individual warnings sent to the contact addresses specified in the ContactInfo field. After the warning, the number of outdated nodes decreased from 1276 to approximately 800. It is preliminarily estimated that currently about 12% of traffic passes through outdated nodes, most of which is related to transit transfer — the share of traffic from outdated exit nodes accounts for only 1.68% (62 nodes). It is anticipated that the removal of outdated nodes from the network will have a minimal impact on the network size and will lead to a slight dip in metrics on graphs , reflecting the state of the anonymous network.The presence of nodes with outdated software negatively affects stability and creates additional security risks. If an administrator does not keep Tor updated, it is likely that they are negligent about updating the system and other server applications, which increases the risk of node takeover due to targeted attacks.

The presence of nodes in the network with outdated software negatively impacts stability and creates additional security breach risks. If an administrator does not keep Tor updated, it is likely that they are careless about updating the system and other server applications, which increases the risk of losing control over the node due to targeted attacks.

Moreover, the presence of nodes with unsupported releases hinders the fixing of critical bugs, obstructs the deployment of new protocol features, and decreases network efficiency. For instance, unresponsive nodes, in which issues arise, error in the HSv3 handler, lead to increased latency for user traffic passing through them and raise the overall network load due to clients sending repeated requests after failures in handling HSv3 connections.

Source: opennet.ru