cyfenced.com →

[ CVE-2026-115778 · Published 23 Oct 2026 ]

Twisted: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer

CVSS 7.5 EPSS <1%Fix available

[ Description ]Official description

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.conch.telnet.Telnet.dataReceived appends every byte received after IAC SB to a persistent subnegotiation buffer until IAC SE is received, without applying a maximum length. Telnet option negotiation occurs before authentication, so an unauthenticated peer can omit the terminator and continuously grow the buffer. The resulting memory exhaustion can terminate the process and every service it hosts. This issue is fixed in version 26.10.0rc1.

[ Fixes ]Fixes and patches

  • Twisted 26.10.0rc1Fixed version · GitHub Advisories · pip package Twisted: upgrade to 26.10.0rc1 or later (affected <= 26.4.0)

[ Packages ]Affected open-source packages

[ References ]References