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TI-2026-55160 Aliases CVE-2026-79662GHSA-m5w8-4879-f4pc

Ech0 before 4.7.3 OAuth Redirect URI Validation Bypass

Priority HIGH 73CWE-601Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
High
Attack requirements
Present
Impact type
Spoofing
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-601.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00321 25th percentileScored 2026-11-07
Fix Fixed Ech0 (lin-snow): 4.7.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
lin-snowEch0before 4.7.34.7.3Patch availableCNA
  • Ech0 Vendorlin-snow Affected before 4.7.3 Fixed in 4.7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:ech0:ech0:*:*:*:*:*:*:*:*——lin-snow
  • cpe:2.3:a:ech0:ech0:*:*:*:*:*:*:*:* Versions — — ·lin-snow

Remediation

  • Fix · CNA Ech0 (lin-snow) Fixed in 4.7.3

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    lin-snow Ech0 4.7.3

    7 records Highest priority Priority HIGH 5 HIGH, 2 LOW

    Other records, highest priority first

    • TI-2026-55162 Ech0 before 4.7.3 Access Token Revocation BypassPriority HIGH 74
    • TI-2026-55159 Ech0 before 4.7.3 Unauthenticated fav_count ModificationPriority HIGH 70
    • TI-2026-55158 Ech0 before 4.7.3 Email Disclosure via Public APIPriority HIGH 70
    Show all 7 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-79662
  2. 2026-10-03 Alias added: GHSA-m5w8-4879-f4pc

References

Advisory 1

  • TI-2026-55162 Ech0 before 4.7.3 Access Token Revocation Bypass CVSS 4.0CRITICAL 9.1
  • TI-2026-55163 Ech0 before 4.5.1 Authorization Bypass via Session Tokens CVSS 4.0HIGH 8.7
  • TI-2026-27239 Ech0 Affected by Unauthenticated Server-Side Request Forgery in Website Preview Feature CVSS 3.1HIGH 7.5
  • TI-2026-27240 Ech0 affected by unauthenticated SSRF in GetWebsiteTitle allows access to internal services and cloud metadata CVSS 3.1HIGH 7.2
  • TI-2026-55159 Ech0 before 4.7.3 Unauthenticated fav_count Modification CVSS 4.0MEDIUM 6.9
  • TI-2026-55158 Ech0 before 4.7.3 Email Disclosure via Public API CVSS 4.0MEDIUM 6.9
See all 19 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences