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.
Published: 2026-10-23
Score: 4.9 Medium
EPSS: n/a
KEV: No
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-2qrf-pqgx-qh9v Twisted: Denial of Service in the Twisted IMAP4 Server via a Negative Literal Size in SEARCH
History

Sat, 24 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Fri, 23 Oct 2026 23:00:00 +0000

Type Values Removed Values Added
First Time appeared Twisted
Twisted twisted
Vendors & Products Twisted
Twisted twisted

Fri, 23 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
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.
Title Twisted: Denial of Service in the Twisted IMAP4 Server via a Negative Literal Size in SEARCH
Weaknesses CWE-400
CWE-835
References
Metrics cvssV3_1

{'score': 4.9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-23T20:14:07.480Z

Reserved: 2026-10-23T13:28:51.847Z

Link: CVE-2026-115774

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-23T21:17:22.900

Modified: 2026-10-23T21:17:22.900

Link: CVE-2026-115774

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-23T20:14:07Z

Links: CVE-2026-115774 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-23T22:45:14Z

Weaknesses
  • CWE-400

    Uncontrolled Resource Consumption

  • CWE-835

    Loop with Unreachable Exit Condition ('Infinite Loop')