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CVE-2026-115778— Twisted: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer

Quick assessment

Affected
twisted twisted
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Twisted 是一个面向互联网应用的事件驱动框架，支持 Python 3.6 及以上版本。在 26.10.0rc1 版本之前， 方法会在接收到 IAC SB 序列后，将后续每个接收到的字节追加到一个持久的子协商缓冲区中，直到收到 IAC SE 序列为止，且未对该缓冲区设置最大长度限制。由于 Telnet 选项协商发生在身份验证之前，未认证的远程对等端可以故意省略终止符，从而持续扩大该缓冲区。由此引发的内存耗尽问题可能导致进程终止，并中断该进程所承载的所有服务。此问题已在 26.10.0rc1 版本中修复。

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-115778

Vulnerability Information
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Vulnerability Title
Twisted: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
twisted twisted < 26.10.0rc1 -

II. Public POCs for CVE-2026-115778

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III. Intelligence Information for CVE-2026-115778

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Patches & Fixes for CVE-2026-115778 (3)

Vendor Advisories for CVE-2026-115778 (1)

Vendor Pages for CVE-2026-115778 (1)

Same Patch Batch · twisted · 2026-10-23 · 6 CVEs total

CVE-2026-115775 8.7 HIGH Twisted: Unauthenticated Remote Denial of Service in the Twisted words domish XML Element
CVE-2026-115776 7.5 HIGH Twisted: Unauthenticated Remote Denial of Service in the Twisted IRC Server via an Unbound
CVE-2026-115877 5.4 MEDIUM Twisted: HTTP Request Smuggling in twisted.web via a Bare CR or LF in a Header Value
CVE-2026-115774 4.9 MEDIUM Twisted: Denial of Service in the Twisted IMAP4 Server via a Negative Literal Size in SEAR
CVE-2026-83813 3.1 LOW Twisted: DNS Response Spoofing in twisted.names Due to Missing Source Address Validation

IV. Related Vulnerabilities

Same product: twisted
Same vendor: twisted
Same weakness: CWE-400

V. Comments for CVE-2026-115778

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