Vulnerability in Tornadoweb Tornado
CVE-2026-49854
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.
EPSS: 0.003 (26.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
Affected products
- Tornadoweb Tornado — versions < 6.5.6
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-49854?
- CVE-2026-49854 is a medium-severity vulnerability in Tornadoweb Tornado, classified under Buffer Over-read. CVSS score: 5.3/10. Published 2026-07-14.
- How severe is CVE-2026-49854?
- Medium severity. CVSS v3 base score is 5.3 out of 10.