Twisted: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer
CVE-2026-115778 is fixed in twisted on 1 platform by DEBIAN-CVE-2026-115778 (version 26.10.0-1), released November 3, 2026. It is not reported as exploited. Patch Radar priority: High.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| twisted · Debian 14 | 26.10.0-1 | DEBIAN-CVE-2026-115778 | Nov 3, 2026 |
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