CVE-2026-42304
Twisted has a Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains
Description
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.
How to fix CVE-2026-42304
To remediate CVE-2026-42304, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 26.4.0rc2 or later
- —upgrade to 26.4.0 or later
Is CVE-2026-42304 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0
- from 0, < 26.4.0rc2
- from 0, < 26.4.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |