NVD / CVE Program· CNA GitHub_M

CVE-2026-42304: Twisted: Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.43% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: twisted twisted 26.4.0rc2; azl3 python-twisted 22.10.0-4 on Azure Linux 3.0 22.10.0-5; azl3 python-twisted 22.10.0-5 on Azure Linux 3.0 22.10.0-5.

Low priority for now. Upgrade to twisted twisted 26.4.0rc2; azl3 python-twisted 22.10.0-4 on Azure Linux 3.0 22.10.0-5; azl3 python-twisted 22.10.0-5 on Azure Linux 3.0 22.10.0-5 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published: May 13, 2026
Updated: Nov 11, 2026
EPSS: 0.4% · 38th percentile
CWE: CWE-400

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.4%

CISA SSVC decision

Exploitation: proof of concept
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 7.5; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
twisted	twisted	cpe:2.3:a:twisted:twisted

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

twisted twistedbefore 26.4.0
twisted twisted26.4.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

twisted twisted
- < 26.4.0rc2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	twisted	from 0	—
Debian:14	twisted	before 26.4.0-1	26.4.0-1
openSUSE:Tumbleweed	python-Twisted	before 26.4.0-1.1	26.4.0-1.1
PyPI	twisted	before 26.4.0rc2	26.4.0rc2
PyPI	twisted	before 26.4.0	26.4.0
SUSE:Linux Enterprise Server 16.0	python-Twisted	before 24.10.0-160000.3.1	24.10.0-160000.3.1

Same product

twisted: all records

Other highest-scoring records for the same primary product.

CVE-2020-10109In Twisted Web through 19.10.0, there was an HTTP request splitting vulnerability.
40Plan
CVE-2020-10108In Twisted Web through 19.10.0, there was an HTTP request splitting vulnerability.
40Plan
CVE-2026-115775Twisted: Unauthenticated Remote Denial of Service in the Twisted words domish XML Element Stream via an Unbounded Element Tree
34Monitor

Published before and after this one in the same product

← EarlierCVE-2024-41671Jul 29, 2024 · twisted.web has disordered HTTP pipeline response
33Monitor
← EarlierCVE-2024-41810Jul 29, 2024 · HTML injection in HTTP redirect body
24Monitor
Later →CVE-2026-106454Oct 6, 2026 · Twisted: IMAP wildcardToRegexp() ReDoS
17Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
twisted twisted	26.4.0rc2 · description	Vendor (CNA)
azl3 python-twisted 22.10.0-4 on Azure Linux 3.0	22.10.0-5 · CBL-Mariner Releases	Microsoft (MSRC)
azl3 python-twisted 22.10.0-5 on Azure Linux 3.0	22.10.0-5 · CBL-Mariner Releases	Microsoft (MSRC)
debian:twisted	26.4.0-1 · Debian:14	Package registry (OSV)
opensuse:python-Twisted	26.4.0-1.1 · openSUSE:Tumbleweed	Package registry (OSV)
PyPI:twisted	26.4.0	Package registry (OSV)
PyPI:twisted	26.4.0rc2	Package registry (OSV)
suse:python-Twisted	24.10.0-160000.3.1 · SUSE:Linux Enterprise Server 16.0	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-115775163 days apartTwisted: Unauthenticated Remote Denial of Service in the Twisted words domish XML Element Stream via an Unbounded Element Tree
34Monitor
CVE-2026-115776163 days apartTwisted: Unauthenticated Remote Denial of Service in the Twisted IRC Server via an Unbounded Line Buffer
30Monitor
CVE-2026-115778163 days apartTwisted: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer
30Monitor
CVE-2026-115774163 days apartTwisted: Denial of Service in the Twisted IMAP4 Server via a Negative Literal Size in SEARCH
19Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Endpoint Denial of ServiceT1499

Change log

Fix✗ → ✓Sep 28, 2026, 10:45 PM UTC

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