What’s Vulnerable › Vulnerabilities

CVE-2026-35536: Tornado has incomplete validation of cookie attributes

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-03 · updated 2026-07-24
• Weakness: CWE-159

Description

In Tornado before 6.5.5, cookie attribute injection could occur because the domain, path, and samesite arguments to .RequestHandler.set_cookie were not checked for crafted characters.

Affected products

• tornadoweb tornado: before 6.5.5 — fixed in 6.5.5
• Pypi Tornado: before 6.5.5; 0.2, 1.0, 1.1, 1.1.1, 1.2, 1.2.1 (+74) — fixed in 6.5.5

How to fix

Upgrade to a fixed version: tornadoweb tornado 6.5.5; Pypi Tornado 6.5.5. Check the vendor advisory for mitigations.

References

• https://github.com/tornadoweb/tornado/releases/tag/v6.5.5
• https://github.com/tornadoweb/tornado/security/advisories/GHSA-78cv-mqj4-43f7

Get alerted when CVE-2026-35536 or the next vulnerability affects your stack