Python tornado: Tornado before 6.6 does not validate the max_age argument of RequestHandler.set_cookie (also called by
Affects python-tornadoSource GCVE Database
Not known to be exploited · CVSS 2.3 Low.
Data as of 12 Nov 2026, 22:18 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 2.3 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 4.2 |
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 8 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 12 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10python-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSpython-tornadopkg:deb/ubuntu/python-tornado?arch=source&distro=esm-apps/bionicOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Until a fix is available, avoid passing untrusted input to the max_age argument in cookie-setting methods to prevent injection of additional Set-Cookie attributes.
Description
Tornado versions before 6.6 do not validate the max_age argument in the RequestHandler.set_cookie method and related cookie-setting methods. This flaw allows an attacker to inject additional Set-Cookie attributes by supplying malicious input as max_age, potentially expanding the cookie's scope to parent paths or other subdomains. The vulnerability has a medium severity rating with a CVSS score of 4.2.
References
- ubuntu.com/security/CVE-2026-123535 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-123535 (opens in a new tab)
- github.com/tornadoweb/tornado/security/advisories/GHSA-c6v4-qj2h-f748 (opens in a new tab)
- github.com/tornadoweb/tornado/pull/3763 (opens in a new tab)
- vulncheck.com/advisories/tornado-before-6.6-cookie-attribute-injection-via-set-cookie-max-age (opens in a new tab)