Bug 2477296 (CVE-2026-42304)

Summary: CVE-2026-42304 python-twisted: Twisted: Denial of Service via crafted DNS packets in twisted.names
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: dschmidt, eglynn, erezende, jjoyce, jlanda, jpretori, jschluet, jwong, kshier, lhh, mburns, mgarciac, omaciel, rhel-process-autobot, simaishi, smcdonal, stcannon, teagle, ttakamiy, 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, specifically within the `twisted.names` module. A remote, unauthenticated attacker can exploit this vulnerability by sending a specially crafted TCP DNS packet containing deeply chained compression pointers. This can lead to resource exhaustion, causing the single-threaded Twisted reactor to hang and effectively freezing the server, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-05-13 21:01:31 UTC
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.