Twisted: Denial of Service in the Twisted IMAP4 Server via a Negative Literal Size in SEARCH

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-115774
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-23 21:17:22 UTC
Updated2026-10-23 21:17:22 UTC
DescriptionTwisted 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.

Risk And Classification

Primary CVSS: v3.1 4.9 MEDIUM from [email protected]

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

Problem Types: CWE-400 | CWE-835 | CWE-400 CWE-400: Uncontrolled Resource Consumption | CWE-835 CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.9MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED4.9MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Twisted Twisted affected < 26.10.0rc1 Not specified

References

ReferenceSourceLinkTags
github.com/twisted/twisted/releases/tag/twisted-26.10.0rc1 [email protected] github.com
github.com/twisted/twisted/security/advisories/GHSA-2qrf-pqgx-qh9v [email protected] github.com
github.com/twisted/twisted/pull/12764 [email protected] github.com
github.com/twisted/twisted/commit/3d125548bcbe955007cb97f480bb699a5e074741 [email protected] github.com
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