Python tornado: Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without
Affects python-tornadoSource GCVE Database
Not known to be exploited · CVSS 5.3 Medium · fixed in 6.5.6 : update python-tornado when convenient.
Data as of 6 Nov 2026, 23:24 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.5.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NExploitation evidence
Disclosed: evidence found.
CVE published 14 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10python-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/bionicOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade Tornado to version 6.5.6 or later, where this issue is fixed. No other mitigation is indicated or required.
Description
A vulnerability in the Python Tornado web framework prior to version 6.5.6 allows the optional native extension tornado.speedups to improperly handle the websocket_mask function. Specifically, it does not validate that the mask argument is exactly four bytes, which can cause the C function to read up to three bytes beyond the intended buffer during Tornado XSRF token decoding when the native extension is active. This issue is fixed in version 6.5.6.
References
- ubuntu.com/security/CVE-2026-49854 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-49854 (opens in a new tab)
- github.com/tornadoweb/tornado/commit/96dc88c2a05705287856b2cd6b4b4034f9a6aaac (opens in a new tab)
- github.com/tornadoweb/tornado/pull/3626 (opens in a new tab)
- github.com/tornadoweb/tornado/releases/tag/v6.5.6 (opens in a new tab)
- github.com/tornadoweb/tornado/security/advisories/GHSA-cx3h-4qpv-8hc9 (opens in a new tab)