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.

Metrics

Attack Vector Network

Attack Complexity High

Privileges Required None

Attack Requirements Present

User Interaction Passive

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact High

Subsequent System Integrity Impact High

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Changed

Confidentiality Impact High

Integrity Impact High

Availability Impact None

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Ech0 Subscribe
Ech0 Subscribe

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No data.

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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/lin-snow/Ech0/security/advisories/GHSA-p64j-f4x9-wq66 cve-icon cve-icon
https://www.vulncheck.com/advisories/ech0-before-oauth-redirect-uri-validation-bypass cve-icon cve-icon
History

Tue, 25 Aug 2026 11:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Ech0 before 4.7.3 OAuth Redirect URI Validation Bypass
First Time appeared Ech0
Ech0 ech0
Weaknesses CWE-601
CPEs cpe:2.3:a:ech0:ech0:*:*:*:*:*:*:*:*
Vendors & Products Ech0
Ech0 ech0
References
Metrics cvssV3_1

{'score': 8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N'}

cvssV4_0

{'score': 8.8, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-25T11:33:26.056Z

Reserved: 2026-08-25T11:09:11.171Z

Link: CVE-2026-79662

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-25T12:16:31.470

Modified: 2026-08-25T12:16:31.470

Link: CVE-2026-79662

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-25T12:30:17Z

Weaknesses