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CVE-2026-115774

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

Published
2026-10-23
Last modified
2026-10-23
CNA
GitHub_M
NVD status
Received
CWE
CWE-400 CWE-835

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CVSS v3.1 (listed by NVD)
4.9
MEDIUM
Scored by github.com (not yet scored by NVD)
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0 (listed by NVD)
—
Not scored
CVSS (listed by CVE.org)
4.9
MEDIUM
Scored by CNA (GitHub_M) · v3.1
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
EPSS exploit probability
0.6%
Percentile 47.4%
as of 2026-10-24
CISA KEV
—
Not listed

Attack conditions and impact

Derived from the CNA (via NVD) CVSS 3.1 vector
NetworkAdminNo interaction Confidentiality NIntegrity NAvailability H
MetricValueMeaning
Attack vector AVNNetwork
Attack complexity ACLLow (easy)
Privileges required PRHAdministrator
User interaction UINNone
Scope SUUnchanged
Confidentiality CNNone
Integrity INNone
Availability AHHigh
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Description

NVD

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.

CVSS assessments

ProviderVersionScoreVector
NVD / [email protected] (Secondary)3.14.9 MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
CNA / GitHub_M3.14.9 MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Affected products and packages

CNA (CVE.org)

VendorProductVersions
twistedtwisted
affected: < 26.10.0rc1

Open-source packages (GitHub Advisory / OSV)

GHSA-2qrf-pqgx-qh9v GHSA MEDIUM reviewed

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

EcosystemPackageAffected versionsFixed in
PyPITwisted<= 26.4.026.10.0rc1

Linux distribution status

Red Hat ↗ moderate

ReleasePackageStatusFixed version / notes
Red Hat Ansible Automation Platform 2ansible-automation-platform-24/controller-rhel8out of support scope
Red Hat Ansible Automation Platform 2ansible-automation-platform-25/controller-rhel8out of support scope
Red Hat Ansible Automation Platform 2ansible-automation-platform-25/lightspeed-rhel8out of support scope
Red Hat Ansible Automation Platform 2ansible-automation-platform-26/controller-rhel9fix deferred
Red Hat Ansible Automation Platform 2ansible-automation-platform-26/eda-controller-rhel9fix deferred
Red Hat Ansible Automation Platform 2ansible-automation-platform-26/lightspeed-rhel9fix deferred
Red Hat Ansible Automation Platform 2ansible-automation-platform-27/controller-rhel9fix deferred
Red Hat Ansible Automation Platform 2ansible-automation-platform-27/eda-controller-rhel9fix deferred
Red Hat Ansible Automation Platform 2ansible-automation-platform-27/lightspeed-rhel9fix deferred
Red Hat Ansible Automation Platform 2automation-controllerfix deferred
Red Hat Ansible Automation Platform 2python-twistedout of support scope
Red Hat OpenStack Platform 16.2python-twistedout of support scope
Red Hat Ansible Automation Platform 2python3.11-twistedfix deferred
Red Hat Ansible Automation Platform 2python3.12-twistedfix deferred
Red Hat Ansible Automation Platform 2python3x-twistedout of support scope

Debian ↗

ReleasePackageStatusFixed version / notes
bookwormtwistedopen not yet assigned
forkytwistedopen not yet assigned
sidtwistedopen not yet assigned
trixietwistedopen not yet assigned no-dsa: Minor issue

Ubuntu ↗ Fetching

References (5)