CVE-2026-123535 Tornado before 6.6 Cookie Attribute Injection via set_cookie max_age
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-123535?
CVE-2026-123535 is a low-severity vulnerability in tornadoweb tornado, published on 8 Nov 2026.
Official description
Tornado before 6.6 does not validate the max_age argument of RequestHandler.set_cookie (also called by set_signed_cookie, set_secure_cookie, and clear_cookie), allowing injection of additional Set-Cookie attributes. When an application passes attacker-influenced input as max_age, an attacker can embed attributes such as Domain, Path, or Secure to widen the cookie's scope to parent paths or other subdomains.
Weakness: CWE-74
Which versions are affected by CVE-2026-123535?
How do I fix CVE-2026-123535?
Upgrade to a fixed version.
Is CVE-2026-123535 being exploited?
There is no known exploitation of CVE-2026-123535 in the wild and no public exploit code.
Sources
Also known as AZL-113107, CLEANSTART-2026-ZY98309, DEBIAN-CVE-2026-123535, GHSA-c6v4-qj2h-f748, GHSA-cfc4-jgx9-vvjh, UBUNTU-CVE-2026-123535.