Open Redirect in Lin-Snow Ech0
CVE-2026-79662
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.
Vulnerability class: Open Redirect
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (23.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 23.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/lin-snow/Ech0/security/advisories/GHSA-p64j-f4x9-wq66 (vendor-advisory)
- www.vulncheck.com/advisories/ech0-before-oauth-redirect-uri-validation-bypass (third-party-advisory)
Frequently asked questions
- What is CVE-2026-79662?
- CVE-2026-79662 is a high-severity vulnerability in Lin-Snow Ech0, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 8.0/10. Published 2026-08-25.
- How severe is CVE-2026-79662?
- High severity. CVSS v3 base score is 8.0 out of 10.