Twisted: Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains
CVE-2026-42304 is fixed in 4 products on 1 platform, first by python3-twisted 22.1.0-2ubuntu2.7, released May 13, 2026. It is not reported as exploited. Patch Radar priority: High.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| python-Twisted · sles 16.0 | 24.10.0-160000.3.1 | SUSE-SU-2026:22004-1 | Jun 1, 2026 |
| python3-twisted · Ubuntu 22.04.1 LTS (jammy) | 22.1.0-2ubuntu2.7 | python3-twisted 22.1.0-2ubuntu2.7 | May 13, 2026 |
| python3-twisted · Ubuntu 24.04.5 LTS (noble) | 24.3.0-1ubuntu0.2 | python3-twisted 24.3.0-1ubuntu0.2 | May 13, 2026 |
| python3-twisted · Ubuntu 25.10 (questing) | 24.11.0-1ubuntu0.1 | python3-twisted 24.11.0-1ubuntu0.1 | May 13, 2026 |
| python3-twisted · Ubuntu 26.04.1 LTS (resolute) | 25.5.0-5ubuntu0.1 | python3-twisted 25.5.0-5ubuntu0.1 | May 13, 2026 |
| python3-twisted · amzn 2023 | 22.4.0-129.amzn2023.0.6 | ALAS2023-2026-1734 | May 25, 2026 |
| python3-twisted+tls · amzn 2023 | 22.4.0-129.amzn2023.0.6 | ALAS2023-2026-1734 | May 25, 2026 |
| twisted · Debian 14 | 26.4.0-1 | DEBIAN-CVE-2026-42304 | May 13, 2026 |
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