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Fencer Vulns
high 7.5

CVE-2026-42304 json

Twisted: Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains

published 2026-05-05 6 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-30158 , GHSA-grgv-6hw6-v9g4 , PYSEC-2026-160

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.4.0rc2, the twisted.names module is vulnerable to a Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. A remote, unauthenticated attacker can exploit this by sending a crafted TCP DNS packet containing deeply chained compression pointers. This flaw bypasses previous loop-prevention logic, causing the single-threaded Twisted reactor to hang while processing millions of recursive lookups, effectively freezing the server. This vulnerability is fixed in 26.4.0rc2.

Patch / fix

  • pypi twisted 26.4.0, 26.4.0rc2
  • twisted twisted 26.4.0rc2
  • twistedmatrix twisted 26.4.0rc2
  • twisted Debian 14 26.4.0-1

debian advisories DEBIAN-CVE-2026-42304

  • twisted Ubuntu 22.04 LTS 22.1.0-2ubuntu2.7
  • twisted Ubuntu 24.04 LTS 24.3.0-1ubuntu0.2
  • twisted Ubuntu 25.10 24.11.0-1ubuntu0.1
  • twisted Ubuntu 26.04 LTS 25.5.0-5ubuntu0.1

ubuntu advisories UBUNTU-CVE-2026-42304

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python-Twisted SLES for SAP applications 16.0, SLES 16.0 24.10.0-160000.3.1

suse advisories SUSE-SU-2026:22004-1

  • python-Twisted openSUSE Tumbleweed 26.4.0-1.1

opensuse advisories openSUSE-SU-2026:10759-1

  • python-twisted Azure Linux 3.0 22.10.0-5

azure linux advisories AZL-86751

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2026-42304 updated cvss 7.5

python-twisted: Twisted: Denial of Service via crafted DNS packets in twisted.names

  • Red Hat Enterprise Linux 6 python-twisted
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Ansible Automation Platform 2 python-twisted, automation-controller, ansible-automation-platform-25/lightspeed-rhel8, ansible-automation-platform-26/controller-rhel9, ansible-automation-platform-26/lightspeed-rhel9, ansible-automation-platform-26/eda-controller-rhel9
    not affected: vulnerable code not present
  • Red Hat Hardened Images python-jsonschema Red Hat OpenStack Platform 16.2 python-twisted, python3-twisted
    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
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/twisted/twisted/security/advisories/GHSA-grgv-6hw6-v9g4 referenced PoC, tagged "exploit" by a source, unverified

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
OSV 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
<26.4.0rc2
<26.4.0
26.4.0rc2
26.4.0

Affected products

  • twisted twisted

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-407 Inefficient Algorithmic Complexity

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.