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Fencer Vulns
high 7.5

CVE-2026-115778 json

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

published 2026-10-23 16 d ago modified 2026-10-26 13 d ago also GHSA-cwm5-jh59-mwxr , EUVD-2026-109151

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 45%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi twisted 26.10.0rc1
  • twisted Debian 14 26.10.0-1

debian advisories DEBIAN-CVE-2026-115778

  • python-Twisted openSUSE Tumbleweed 26.10.0-1.1

opensuse advisories openSUSE-SU-2026:12381-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-115778 updated cvss 7.5

twisted: twisted: Denial of Service via memory exhaustion during Telnet negotiation

  • Red Hat Ansible Automation Platform 2 python-twisted 23.10.0-1.el9ap, python3x-twisted 23.10.0-1.el8ap, python3.11-twisted 24.7.0-1.el9ap, python3.12-twisted 24.7.0-2.el9ap, automation-controller 4.7.18-1.el9ap, ansible-automation-platform-24/controller-rhel8, +6 more
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/lightspeed-rhel9, ansible-automation-platform-27/lightspeed-rhel9 Red Hat OpenStack Platform 16.2 python3-twisted, python-twisted 23.10.0-1.el9ap
    not affected: vulnerable code not in execute path

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
16 d ago

Exploit prediction

0.54% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi twisted
<26.10.0rc1
26.10.0rc1

Affected products

  • twisted twisted

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.