VulnerabilityPublished 29 Oct 2026

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

Affects livereloadSource GCVE Database

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Authoritative record:CVE-2026-116578· Low 2.1

Not known to be exploited · CVSS 2.1 Low · fixed in 6.6 : update livereload when convenient.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score

2.1Low

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 4.0	2.1

EPSS: 0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 6.6

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: Active
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: Low
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: Active: Successful exploitation of this vulnerability requires a targeted user to perform specific, conscious interactions with the vulnerable system and the attacker’s payload, or the user’s interactions would actively subvert protection mechanisms which would lead to exploitation of the vulnerability.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Subsequent System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 Oct 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 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Homebrewlivereload`pkg:brew/livereload`Other threats	Affected >=2.7.1	Fixed in–

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AI-suggested

Upgrade to Tornado 6.6 or later, where the vulnerability is fixed by rejecting redirects that alter the scheme or host. Alternatively, modify RedirectHandler templates so that substitutions occur only after a fixed prefix ending with a slash, or implement a custom redirect handler that validates redirect targets before redirecting. No other actions are required if using static URLs or safe substitution patterns.

Description

CVE-2026-116578 is an open redirect vulnerability in Tornado's RedirectHandler. It occurs when URL templates use regex capture groups that influence the scheme or host of the redirect target, allowing attackers to craft URLs that redirect users to arbitrary external sites. This can facilitate phishing attacks. The vulnerability is fixed in Tornado 6.6, which rejects redirects that alter the scheme or host. Applications using static URLs or substitutions only after a fixed host and slash are not affected.

Impact

Applications using vulnerable RedirectHandler templates can be tricked into redirecting users to attacker-controlled domains, enabling phishing attacks by exploiting the trust in the original domain. The CVSS score is low (2.1) reflecting limited impact and complexity, but the vulnerability still poses a risk of user redirection to malicious sites.

Summary

The vulnerability in tornado.web.RedirectHandler arises from how it builds redirect URLs by substituting parts of the request path into a template. If the template allows substitutions at the start of the path or immediately after the host, an attacker can manipulate the redirect target to an arbitrary host using protocol-relative URLs or crafted paths. This leads to open redirect behavior on the application's domain. Tornado 6.6 fixes this by returning a 400 error when substitutions would change the scheme or host, preventing such redirects. Workarounds include restricting substitutions to after a fixed prefix or validating redirect targets manually.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Oct 2026, 18:52 UTC

Technical details

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