CVE Intelligence
Low Open redirect

CVE-2026-116578 — Tornado: Open redirect in RedirectHandler via protocol-relative URLs

Tornado is a Python web framework and asynchronous networking library. Prior to 6.6, tornado.web.RedirectHandler URL templates can place regex-capture substitutions where crafted request paths change the redirect scheme or network location. Affected placements include substitutions at the start of a path, directly after a fixed host, or at the beginning of the template, including protocol-relative, absolute, backslash, encoded, host-extension, and user-info variants interpreted by browsers as attacker-controlled destinations. Static templates and substitutions after a fixed host followed by a slash are not affected. An attacker can use the resulting open redirect on the application's domain for phishing. This issue is fixed in version 6.6.

Published Oct 26, 2026 · Updated Oct 26, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database · CNA: GitHub_M

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • No scoring signals.

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
—
No EPSS score.
Affects
Tornadoweb
Tornado
CVSS base
2.1
Low · 2 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Tornadoweb Tornado).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  5. Search available logs for exploit probes matching the vulnerability class (open redirect), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Tornadoweb Tornado version < 6.6 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Attack requirements
Present
Privileges required
None
User interaction
Active
Scope
X
Confidentiality (vulnerable system)
None
Integrity (vulnerable system)
None
Availability (vulnerable system)
None
Confidentiality (subsequent)
None
Integrity (subsequent)
Low
Availability (subsequent)
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
2.1 CVSS 4.0 Low — — security-advisories@github.com via NIST National Vulnerability Database
2.1 CVSS 4.0 Low — — GitHub_M via CVE Program (cve.org) e CISA ADP
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X (score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-601 · Open Redirect

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Source status changed · Published → Deferred
    Oct 26, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 26, 2026
  • CVSS changed · 2.1
    Oct 26, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 26, 2026 · CVE Program (cve.org) e CISA ADP
  • Record created in this database
    Oct 26, 2026 · CVE Program (cve.org) e CISA ADP
  • CVE published
    Oct 26, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 26, 2026 – Oct 26, 2026

References

6 on the record

Elsewhere on this site

Tornadoweb
every CVE for this vendor
Open redirect
same class
CWE-601
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-116577 Tornado: Quadratic CPU usage when parsing HTTP headers with line folding 5h
  • CVE-2026-115927 Tornado: Event loop blocking and excess memory use from chunked bodies with many small chunks 6h
  • CVE-2026-103263 Tornado before 6.5.9 StaticFileHandler Path Traversal via Symlink 25d
  • CVE-2026-103262 Tornado before 6.5.9 Denial of Service via CurlAsyncHTTPClient 25d
  • CVE-2026-103261 Tornado before 6.5.9 Denial of Service via Query String 25d
  • CVE-2026-91991 Tornado before 6.5.8 Cookie Attribute Injection via Capitalized kwargs Sep 15, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No FIRST EPSS score.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-116578 is "Tornado: Open redirect in RedirectHandler via protocol-relative URLs", rated Low. It affects Tornado (Tornadoweb); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 2.1 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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