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

Exp

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: 2026-05-13 Last update: 2026-05-19 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-42304 is rated Exploit Available (50/100): CVSS High severity, with low exploitation likelihood (EPSS 0.01%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-42304

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-42304

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-14 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-42304

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-42304

GitHub Security Advisory for CVE-2026-42304

GHSA-grgv-6hw6-v9g4 · Severity: high · Ecosystem: pip — Twisted has a Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains

OS Trackers for CVE-2026-42304

vendor priority summary link
debian not yet assigned CVE-2026-42304 not yet assigned priority: Debian including 1 source packages (twisted), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 4, resolved 1. https://security-tracker.debian.org/tracker/CVE-2026-42304
suse medium CVE-2026-42304 severity moderate: SUSE including 25 source package names (python-Twisted-doc-26.4.0-1.1, python311-Twisted-26.4.0-1.1, …), 25 product×package rows across 1 product lines (openSUSE Tumbleweed): Fixed 25. https://www.suse.com/security/cve/CVE-2026-42304/
ubuntu medium CVE-2026-42304 medium priority: Ubuntu including 1 source packages (twisted), 9 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): needs-triage 8, released 1. https://ubuntu.com/security/CVE-2026-42304

Affected software / configurations for CVE-2026-42304

Vendor Product Version Raw CPE
twisted twisted < 26.4.0 cpe:2.3:a:twisted:twisted:*:*:*:*:*:*:*:*
twisted twisted 26.4.0 cpe:2.3:a:twisted:twisted:26.4.0:rc1:*:*:*:*:*:*

References for CVE-2026-42304

cvelogic Threat Intelligence