Bug 2501086

Summary: CVE-2026-49854 python-tornado: Tornado: Information disclosure via out-of-bounds read in websocket_mask [fedora-all]
Product: [Fedora] Fedora Reporter: Ganesh <gnaik>
Component: python-tornadoAssignee: Robby Callicotte <rcallicotte>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: 45CC: aurelien, gwync, mhroncok, orion, python-packagers-sig, rcallicotte
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 19:37:53 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.
Comment 1 Aoife Moloney 2026-08-17 15:20:41 UTC 
This bug appears to have been reported against 'rawhide' during the Fedora Linux 45 development cycle.
Changing version to 45.