CVE-2026-49854

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

Published Jul 14, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Github GHSA Github GHSA GHSA-cx3h-4qpv-8hc9 Tornado has out-of-bounds memory access via C extension
History
Type Values Removed Values Added
First Time appeared Tornadoweb
Tornadoweb tornado
Vendors & Products Tornadoweb
Tornadoweb tornado
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title Tornado: Out-of-bounds memory access in C extension
Weaknesses CWE-126
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 15, 2026, 1:26 PM
Reserved
Jun 1, 2026, 10:03 PM
Status
Deferred
Published
Jul 14, 2026, 9:17 PM
Modified
Oct 24, 2026, 9:10 PM
Severity
Moderate
Public date
Jul 14, 2026, 8:43 PM