Bug 2560186 (CVE-2026-83813)

Summary: CVE-2026-83813 twisted: twisted: DNS spoofing via missing response source verification
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: dschmidt, eglynn, jjoyce, jlanda, jpretori, jschluet, jwong, kshier, lhh, mburns, mgarciac, omaciel, rbobbitt, rhel-process-autobot, simaishi, stcannon, tguha, watson-tool-maintainers, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Twisted. This vulnerability allows a network attacker to spoof Domain Name System (DNS) responses and redirect network traffic. The DNS protocol implementation accepts incoming User Datagram Protocol (UDP) responses that match a pending query transaction identifier without validating that the packet originated from the queried server address and port. By delivering a packet with the correct transaction identifier to the listening resolver, an attacker can inject forged answers and manipulate hostname resolution.
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Description OSIDB Bzimport 2026-10-23 20:41:40 UTC 
Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.names.dns.DNSDatagramProtocol accepts a UDP DNS response for a pending query when its 16-bit transaction ID matches but does not verify that the response came from the queried host and port. An attacker able to deliver a packet to the resolver's listening port with the correct transaction ID can inject a forged answer. The standard twisted.names.client.Resolver uses a new random source port for each query, increasing off-path attack complexity, while applications that reuse a DNSDatagramProtocol instance expose only the transaction-ID search space after the first query. A successful forgery can redirect hostname resolution and enable mail interception, server-side request forgery, or man-in-the-middle positioning. This issue is fixed in version 26.10.0rc1.