GHSA-p9f5-h3rx-j5qw: Gogs Missing Authorization in Attachment Download

Summary In Gogs 0.14.1, GET /attachments/:uuid returns the raw attachment file without verifying whether the requester has view permission for the associated Issue/Comment/Release or the repository. In a test environment with REQUIRE_SIGNIN_VIEW = false, we confirmed that an unauthenticated user can download attachments belonging to a private repository. Description /attachments/:uuid retrieves an attachment record solely by the UUID provided in the URL and returns the corresponding local file without performing any authorization checks against the attachment’s parent object (Issue/Comment/Release) or the repository it belongs to. As a result, even attachments under private repositories can be downloaded by an unauthenticated user (or a user without proper permissions) as long as the UUID is known. Relevant code (internal/cmd/web.go:306): m.Get("/attachments/:uuid", func(c *context.Context) { attach, err := database.GetAttachmentByUUID(c.Params(":uuid")) if err != nil { c.NotFoundOrError(err, "get attachment by UUID") return } else if !com.IsFile(attach.LocalPath()) { c.NotFound() return } fr, err := os.Open(attach.LocalPath()) if err != nil { c.Error(err, "open attachment file") return } defer fr.Close() c.Header().Set("Content-Security-Policy", "default-src 'none'; style-src 'unsafe-inline'; sandbox") c.Header().Set("Cache-Control", "public,max-age=86400") c.Header().Set("Content-Disposition", fmt.Sprintf(inline; filename="%s", attach.Name)) if _, err = io.Copy(c.Resp, fr); err != nil { c.Error(err, "copy from file to response") return } }) The UUID lookup itself also performs no validation tied to repository visibility or user permissions. Authorization is not enforced at this layer. Relevant code (internal/database/attachment.go:124): // GetAttachmentByUUID returns attachment by given UUID. func GetAttachmentByUUID(uuid string) (*Attachment, error) { return getAttachmentByUUID(x, uuid) } Preconditions - The attacker knows the target attachment’s UUI