CVE-2026-115778 Twisted: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-115778?
CVE-2026-115778 is a high-severity vulnerability in twisted, published on 23 Oct 2026.
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.
Which versions are affected by CVE-2026-115778?
2 open source packages ship an affected version, including Twisted and twisted.
| Package | Affected | Fixed in |
|---|---|---|
Twisted PyPI | All versions | 26.10.0rc1 |
twisted PyPI | All versions | 26.10.0rc1 |
How do I fix CVE-2026-115778?
Upgrade Twisted to 26.10.0rc1 or later.
Is CVE-2026-115778 being exploited?
There is no known exploitation of CVE-2026-115778 in the wild and no public exploit code.
Sources
Also known as AZL-111413, DEBIAN-CVE-2026-115778, ECHO-27c0-b1bd-95d4, GHSA-cwm5-jh59-mwxr, UBUNTU-CVE-2026-115778.