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Fencer Vulns
medium 4.9

CVE-2026-115774 json

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

published 2026-10-23 16 d ago modified 2026-10-29 10 d ago also GHSA-2qrf-pqgx-qh9v , EUVD-2026-109148

cvss
4.9
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 44%
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.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.

Patch / fix

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

debian advisories DEBIAN-CVE-2026-115774

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-2026-115774 updated cvss 6.5

twisted: twisted: Denial of Service via negative size in IMAP search command

  • 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, +8 more
    affected: no fix available, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 6 python-twisted 23.10.0-1.el9ap Red Hat OpenStack Platform 13 (Queens) python-twisted 23.10.0-1.el9ap
    affected: no fix available “Fix deferred”
  • Red Hat OpenStack Platform 16.2 python3-twisted, python-twisted 23.10.0-1.el9ap
    affected: no fix planned “Out of support scope”

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
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
10 d ago

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/twisted/twisted/security/advisories/GHSA-2qrf-pqgx-qh9v referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/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-835 Loop with Unreachable Exit Condition

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.