CVE-2026-49854

MEDIUM5.3

Tornado: Out-of-bounds memory access in C extension

Published Jul 14, 2026

Modified 1 weeks ago

Details

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.

References

WEB

https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac

WEB

https://github.com/tornadoweb/tornado/pull/3626

WEB

https://github.com/tornadoweb/tornado/releases/tag/v6.5.6

WEB

https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-49854

CVSS Analysis