HTTP Response Splitting Affecting py3.13-tornado package, versions <6.5.8-r0


Severity

Recommended
0.0
medium
0
10

Snyk's Security Team recommends NVD's CVSS assessment. Learn more

Threat Intelligence

EPSS
0.25% (15th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-MINIMOSLATEST-PY313TORNADO-20941709
  • published15 Oct 2026
  • disclosed15 Sept 2026

Introduced: 15 Sep 2026

CVE-2026-91991  (opens in a new tab)
CWE-113  (opens in a new tab)

How to fix?

Upgrade Minimos:latest py3.13-tornado to version 6.5.8-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream py3.13-tornado package and not the py3.13-tornado package as distributed by Minimos. See How to fix? for Minimos:latest relevant fixed versions and status.

Tornado before 6.5.8 contains an incomplete fix for cookie attribute injection that allows attackers to inject arbitrary cookie attributes by passing capitalized or legacy keyword arguments to set_cookie. Attackers can embed semicolon-delimited data in capitalized parameters like Domain, Path, or SameSite to bypass validation and modify cookie security attributes.

CVSS Base Scores

version 3.1