lin-snow Ech0 up to 4.7.2 Redirect URI Validation auth.go parseAndValidateClientRedirect redirect_uri

Summaryinfo

A vulnerability, which was classified as problematic, has been found in lin-snow Ech0 up to 4.7.2. This issue affects the function parseAndValidateClientRedirect of the file internal/service/auth/auth.go of the component Redirect URI Validation. Performing a manipulation of the argument redirect_uri results in redirect. This vulnerability is known as CVE-2026-79662. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in lin-snow Ech0 up to 4.7.2. It has been classified as problematic. This affects the function parseAndValidateClientRedirect of the file internal/service/auth/auth.go of the component Redirect URI Validation. The manipulation of the argument redirect_uri with an unknown input leads to a redirect vulnerability. CWE is classifying the issue as CWE-601. A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. This is going to have an impact on integrity. The summary by CVE is:

Ech0 through 4.5.6 contains an OAuth redirect URI validation vulnerability in parseAndValidateClientRedirect (internal/service/auth/auth.go) that compares only the scheme and host of the client-supplied redirect_uri against the admin-configured allowlist, ignoring path, query, and fragment components. The redirect_uri is embedded into the signed state JWT at login time without validation. An attacker can craft a redirect_uri whose host matches an allowed origin but whose path is attacker-influenced; after the OAuth exchange the victim is redirected to that path with a one-time exchange code in the query string. If the code leaks (e.g., via Referer, analytics, or an open redirect on that host), the attacker can trade it at the public POST /api/auth/exchange endpoint for the victim's access and refresh tokens. Fixed in 4.7.3.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-79662 since 08/25/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1204.001 for this issue.

Upgrading to version 4.7.3 eliminates this vulnerability.

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Productinfo

Vendor

• lin-snow

Name

• Ech0

Version

• 4.7.0
• 4.7.1
• 4.7.2

Website

• Product: https://github.com/lin-snow/Ech0/

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