Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') Affecting tornado package, versions [6.5.5, 6.5.8)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-TORNADO-19498530
- published2 Sept 2026
- disclosed1 Sept 2026
- creditUnknown
Introduced: 1 Sep 2026
NewCVE-2026-91991 (opens in a new tab)How to fix?
Upgrade tornado to version 6.5.8 or higher.
Overview
tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.
Affected versions of this package are vulnerable to Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') via the set_cookie method when attacker-controlled keyword arguments with capitalized names are passed, bypassing character validation and allowing injection of arbitrary cookie attributes. An attacker can manipulate cookie attributes by supplying specially crafted values through capitalized keyword arguments.
Note: This is only exploitable if the application uses capitalized or legacy keyword arguments in the set_cookie method.