chore(deps): update dependency tornado to v6.5.6 [security]

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
tornado (source)	6.5.5 → 6.5.6

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Tornado has out-of-bounds memory access via C extension

CVE-2026-49854 / GHSA-cx3h-4qpv-8hc9

More information

Details

Summary

Tornado's optional native extension tornado.speedups implements websocket_mask without validating that the mask argument is exactly four bytes long. The C function reads four bytes from mask unconditionally, even when Python passes a shorter byte string. This can read beyond the provided buffer, exposing up to 3 bytes of uninitialized memory.

The behavior is reachable from Tornado's XSRF token decoder when xsrf_cookies=True and the native extension is active.

Mitigations

This bug is fixed in Tornado 6.5.6. Prior to upgrading to this version, setting the environment variable TORNADO_EXTENSION=0 will disable the vulnerable code (at the expense of reducing websocket performance).

Severity

• CVSS Score: 3.7 / 10 (Low)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

References

• https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9
• https://github.com/tornadoweb/tornado/releases/tag/v6.5.6
• https://github.com/advisories/GHSA-cx3h-4qpv-8hc9

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

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Release Notes

tornadoweb/tornado (tornado)

v6.5.6

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