Bug 2501090

Summary: CVE-2026-49854 python-flit: Tornado: Information disclosure via out-of-bounds read in websocket_mask [fedora-all]
Product: [Fedora] Fedora Reporter: Ganesh <gnaik>
Component: python-flitAssignee: Maxwell G <maxwell>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: rawhideCC: epel-packagers-sig, maxwell, michel, python-packagers-sig
Target Milestone: ---Keywords: Security, SecurityTracking
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Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["86cf8e91-b2a3-4a38-8279-ff6e3c65d315"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2500661    

Description Ganesh 2026-07-15 19:41:26 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6.