Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.words.protocols.irc.IRC.dataReceived retains all bytes received without a line feed in its per-connection buffer and applies no maximum line length. The twisted.words.service.IRCUser server subclass inherits this behavior, and buffering occurs before PASS, NICK, or USER authentication commands. An unauthenticated connection can continuously grow the buffer until the shared server process runs out of memory and drops all users. This issue is fixed in version 26.10.0rc1.
https://github.com/twisted/twisted/security/advisories/GHSA-53xc-49m8-p798
https://github.com/twisted/twisted/releases/tag/twisted-26.10.0rc1
https://github.com/twisted/twisted/pull/12771
https://github.com/twisted/twisted/commit/ac90fb7b0ab73688a581fcd9a7c0577ec8ca3059
https://github.com/twisted/twisted/commit/01f8cff7753c1edac132380b2ea939fa6bdbab30