Skip to main content
CVE-2026-49854VulnerabilityPublished Updated

Python tornado: Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without

Affects python-tornadoSource GCVE Database

0
Compare
Authoritative record:CVE-2026-49854· Medium 5.3

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

CVSS 3.1 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
Ubuntu 26.10python-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=stonkingOther threatsAffected
  • 6.5.4-0.1 – 6.5.5-5ubuntu1.2
6 affected builds
Fixed in–
Ubuntu 26.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=resoluteOther threatsAffected
  • 6.4.2-3 – 6.5.4-0.1ubuntu0.3
6 affected builds
Fixed in–
Ubuntu 24.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=nobleOther threatsAffected
  • 6.3.2-1 – 6.4.0-1ubuntu0.7
10 affected builds
Fixed in–
Ubuntu Pro 22.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/jammyOther threatsAffected
  • 6.1.0-1build1 – 6.1.0-3ubuntu0.1~esm7
10 affected builds
Fixed in–
Ubuntu Pro 20.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/focalOther threatsAffected
  • 5.1.1-4ubuntu1 – 6.0.3+really5.1.1-3ubuntu0.1~esm8
11 affected builds
Fixed in–
Ubuntu Pro 18.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/bionicOther threatsAffected
  • 4.5.1-2.1~build2 – 4.5.3-1ubuntu0.2+esm5
10 affected builds
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

Community reviews

Loading reviews…