CVE-2026-49854
Tornado: Out-of-bounds memory access in C extension
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Timeline
ID reserved
By GitHub_M
- 43 days later
· 43 days later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
| NVDNVD · Deferred | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.42% · top 64% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Weakness
Affected products
- affected < 6.5.6
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- PyPItornadoGHSA-cx3h-4qpv-8hc9 (opens in a new tab)
References (4)
- https://github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/tornadoweb/tornado/pull/3626 (opens in a new tab)x_refsource_MISC
- https://github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac (opens in a new tab)x_refsource_MISC
- https://github.com/tornadoweb/tornado/releases/tag/v6.5.6 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-cx3h-4qpv-8hc9 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-49854)Record last updated .