CVE-2026-115778

High

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.

SeverityHigh

CVSS7.5

Exploit probability—

Product

Twisted

PublishedOct 23, 2026

First seenOct 23, 2026

Weakness typeCWE-400Uncontrolled resource consumption CWE-770Allocation of resources without limits

How to fix

Update

twisted26.10.0rc1 or later

Affected products

Product	Affected versions	Fixed in
twistedPyPI	v < 26.10.0rc1	26.10.0rc1
microsoft azl3_python-twisted_22.10.0-6	No range specified	—
microsoft azl3_python-twisted_22.10.0-7	No range specified	—

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