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Fencer Vulns
high 8.0

CVE-2026-79662 json

Ech0 before 4.7.3 OAuth Redirect URI Validation Bypass

published 2026-05-07 6 mo ago modified 2026-08-31 2 mo ago also EUVD-2026-65452 , GHSA-p64j-f4x9-wq66 , GO-2026-5531

cvss
8.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

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.

Patch / fix

  • go github.com/lin-snow/Ech0 1.4.8-0.20260503040728-a7e8b8e84bd1
  • go github.com/lin-snow/ech0 1.4.8-0.20260503040728-a7e8b8e84bd1
  • lin-snow Ech0 4.7.3

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
2 mo ago

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/lin-snow/Ech0/security/advisories/GHSA-p64j-f4x9-wq66 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.8 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
CNA 3.1 8.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
GitHub 3.1 8.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
CNA 4.0 8.8 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
go github.com/lin-snow/Ech0
<1.4.8-0.20260503040728-a7e8b8e84bd1
1.4.8-0.20260503040728-a7e8b8e84bd1
go github.com/lin-snow/ech0
<1.4.8-0.20260503040728-a7e8b8e84bd1
1.4.8-0.20260503040728-a7e8b8e84bd1

Affected products

  • lin-snow Ech0

Classification

Weakness
  • CWE-601 URL Redirection to Untrusted Site
  • CWE-1173 Improper Use of Validation Framework

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.