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CVE-2026-115778

SSVC: none

Twisted: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer

Published
2026-10-23
Last modified
2026-10-23
CNA
GitHub_M
NVD status
Received
CWE
CWE-400 CWE-770

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CVSS v3.1 (listed by NVD)
7.5
HIGH
Scored by github.com (not yet scored by NVD)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0 (listed by NVD)
—
Not scored
CVSS (listed by CVE.org)
7.5
HIGH
Scored by CNA (GitHub_M) · v3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS exploit probability
0.7%
Percentile 54.2%
as of 2026-10-24
CISA KEV
—
Not listed
SSVC (CISA ADP)
none
Automatable: yes / Impact: partial

Attack conditions and impact

Derived from the CNA (via NVD) CVSS 3.1 vector
NetworkNo authNo interaction Confidentiality NIntegrity NAvailability H

This vulnerability may be exploitable over the internet without authentication or user interaction.

MetricValueMeaning
Attack vector AVNNetwork
Attack complexity ACLLow (easy)
Privileges required PRNNone
User interaction UINNone
Scope SUUnchanged
Confidentiality CNNone
Integrity INNone
Availability AHHigh
CVSS:3.1/AV:N/AC:L/PR:N/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.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.

CVSS assessments

ProviderVersionScoreVector
NVD / [email protected] (Secondary)3.17.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA / GitHub_M3.17.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/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-cwm5-jh59-mwxr GHSA HIGH reviewed

Twisted: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer

EcosystemPackageAffected versionsFixed in
PyPITwisted<= 26.4.026.10.0rc1

Linux distribution status

Red Hat ↗ important

ReleasePackageStatusFixed version / notes
Red Hat Ansible Automation Platform 2ansible-automation-platform-24/controller-rhel8fix deferred
Red Hat Ansible Automation Platform 2ansible-automation-platform-25/controller-rhel8fix deferred
Red Hat Ansible Automation Platform 2ansible-automation-platform-25/lightspeed-rhel8fix deferred
Red Hat Ansible Automation Platform 2ansible-automation-platform-26/controller-rhel9affected
Red Hat Ansible Automation Platform 2ansible-automation-platform-26/eda-controller-rhel9affected
Red Hat Ansible Automation Platform 2ansible-automation-platform-26/lightspeed-rhel9affected
Red Hat Ansible Automation Platform 2ansible-automation-platform-27/controller-rhel9affected
Red Hat Ansible Automation Platform 2ansible-automation-platform-27/eda-controller-rhel9affected
Red Hat Ansible Automation Platform 2ansible-automation-platform-27/lightspeed-rhel9affected
Red Hat Ansible Automation Platform 2automation-controlleraffected
Red Hat Ansible Automation Platform 2python-twistedfix deferred
Red Hat OpenStack Platform 16.2python-twistedaffected
Red Hat Ansible Automation Platform 2python3.11-twistedaffected
Red Hat Ansible Automation Platform 2python3.12-twistedaffected
Red Hat Ansible Automation Platform 2python3x-twistedfix deferred

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 (6)