CVE-2026-126347 json
Tornado: Open redirect via triple-slash redirect paths
published 5d ago modified yesterday also EUVD-2026-124727 , GHSA-5cjw-f85j-cv6r
- cvss
- 3.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 5%
- public exploits
- 0
- none known
Summary
Tornado is a Python web framework and asynchronous networking library. In versions through 6.6.0, applications using tornado.web.RedirectHandler with URL templates that allow attacker-controlled substitutions to influence the destination can be vulnerable to an open redirect using three or more leading slashes. Differences between Python’s URL parsing and browser URL interpretation allow a crafted destination to redirect a user to an attacker-controlled host. The remediation for CVE-2026-116578 in version 6.6.0 did not fully address this case. This issue is fixed in version 6.6.1.
Patch / fix
- pypi tornado 6.6.1
Is CVE-2026-126347 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- yesterday
Exploit prediction
0.16% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-14).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N |
| GitHub | 3.1 | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | tornado | <6.6.1 |
6.6.1 |
Affected products
- tornadoweb tornado
Classification
- Weakness
-
- CWE-601 URL Redirection to Untrusted Site
References
-
github.com
/tornadoweb/tornado/commit/c503241622c0efe7c40110d89834ce8b7fead1e4
web
-
github.com
/tornadoweb/tornado/security/advisories/GHSA-5cjw-f85j-cv6r
web, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-126347
advisory
-
github.com
/tornadoweb/tornado
package
-
github.com
/tornadoweb/tornado/releases/tag/v6.6.1
web
Sources
- CVE List CVE-2026-126347
- GitHub Advisory GHSA-5cjw-f85j-cv6r
- NVD CVE-2026-126347
- Maintainer advisory GHSA-5cjw-f85j-cv6r
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of tornadoweb/tornado published their own advisory on GitHub. Reviewed sources take precedence over it.