CVE-2026-49854CWE-126

CVE-2026-49854

Medium · published July 15, 2026

CVSS v3.1
5.3
EPSS
0%
Percentile
35.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00419 · 35.1th percentile
Weakness
CWE-126 · Buffer Over-read
Published
2026-07-15T01:17Z
References (4)
https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac · [email protected]https://github.com/tornadoweb/tornado/pull/3626 · [email protected]https://github.com/tornadoweb/tornado/releases/tag/v6.5.6 · [email protected]https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9 · [email protected]
EPSS history
Timeline
  • 14 JUL 20:43Z
    Tornado: Out-of-bounds memory access in C extension
    cvelistv5