3.1 Low

Twisted: DNS Response Spoofing in twisted.names Due to Missing Source Address Validation

CVE-2026-83813

Summary twisted.names.dns.DNSDatagramProtocol, the UDP transport used by twisted's DNS client (twisted.names.client.Resolver, createResolver, and anything built on it, including MX lookups in twisted.mail), accepts a DNS response for a pending query solely on the basis of the 16-bit transaction ID matching. It never checks that the response actually originated from the server the query was sent to. Any host that can deliver a UDP packet to the resolver's listening port with the correct transaction ID can inject a forged answer, independent of the real server's address. This is a materially weaker defense than standard DNS resolver practice (transaction ID plus source-address validation, typically also source-port rotation), and enables off-path DNS response spoofing / cache poisoning. Details DNSDatagramProtocol.datagramReceived (src/twisted/names/dns.py, line 3350) is: python def datagramReceived(self, data, addr): """ Read a datagram, extract the message in it and trigger the associated Deferred. """ m = Message() try: m.fromStr(data) except EOFError: ... except ValueError as ex: ... except BaseException: ... if m.id in self.liveMessages: d, canceller = self.liveMessages[m.id]…

Assessment

CVSS: 3.1 (v3.1)
Severity: Low
EPSS: 0.00114% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 27 October 2026
Last updated: 27 October 2026
Affected: pip · Twisted
Weakness: CWE-346

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

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