CVE-2026-115774: DoS (CVSS 4.9)

Description

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.mail.imap4.IMAP4Server reaches twisted.mail.imap4.parseNestedParens with a negative literal size in an authenticated SEARCH command after the client enters the selected mailbox state. The negative size moves the parser cursor below zero, and Python's negative indexing prevents the synchronous scanning loop from terminating. The loop freezes the single-threaded reactor, stopping other IMAP connections and any SMTP or POP3 services hosted in the same process until restart. This issue is fixed in version 26.10.0rc1.

Is your site exposed to CVE-2026-115774?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.9

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-400 Uncontrolled Resource Consumption

CWE-835 CWE-835

References

Other References

https://github.com/twisted/twisted/commit/3d125548bcbe955007cb97f480bb699a5e074741 https://github.com/twisted/twisted/pull/12764 https://github.com/twisted/twisted/releases/tag/twisted-26.10.0rc1 https://github.com/twisted/twisted/security/advisories/GHSA-2qrf-pqgx-qh9v

Frequently Asked Questions

What is CVE-2026-115774? +

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.mail.imap4.IMAP4Server reaches twisted.mail.imap4.parseNestedParens with a negative literal size in an authenticated SEARCH command after the client enters the selected mailbox state. The negative size moves the parser cursor below zero, and Python's negative indexing prevents the synchronous scanning loop from terminating. The loop freezes the single-threaded reactor, stopping other IMAP connections and any SMTP or POP3 services hosted in the same process until restart. This issue is fixed in version 26.10.0rc1. It has a CVSS v3.1 base score of 4.9 (MEDIUM).

How severe is CVE-2026-115774? +

CVE-2026-115774 has a CVSS v3.1 score of 4.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-115774? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-45802

FPDI is a collection of PHP classes that facilitate reading pages from existing PDF documents and using them as templates …

CVE-2026-101911

ip-address is a library for parsing and manipulating IPv4 and IPv6 addresses in JavaScript. Prior to 10.7.1, the Address6 constructor, …

CVE-2026-67318

axios versions >=1.13.0 (Node.js HTTP adapter) fail to enforce the configured maxBodyLength limit on streamed request bodies when requests are …

CVE-2026-42343

FastGPT is an AI Agent building platform. In versions 4.14.13 and prior, the code-sandbox component suffers from insufficient resource isolation …

CVE-2026-66071

RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom …

CVE-2026-67226

RabbitMQ is a messaging and streaming broker. From 4.0.0 until 4.0.22 and 4.1.14 and 4.2.7, Admin-only atom exhaustion: PUT /api/users …

CVE-2026-115774