The ingredients in Oreo cookies are as follows:

• SUGAR: Halal
• UNBLEACHED ENRICHED FLOUR (Wheat Flour, Niacin, Reduced Iron, Thiamine Mononitrate {Vitamin B1}, Riboflavin {Vitamin B2}, Folic Acid): Halal
• PALM OIL: Halal
• SOYBEAN AND/OR CANOLA OIL: Halal
• COCOA (Processed with Alkali): Halal
• HIGH FRUCTOSE CORN SYRUP: Halal
• BAKING SODA: Halal
• SALT: Halal
• SOY LECITHIN: Questioned (depends on the source)
• CHOCOLATE: Halal
• ARTIFICIAL FLAVOR: Questioned (depends on the source)

While the ingredients themselves do not contain obvious haram substances, the absence of a Halal certification means that it is not guaranteed to meet Halal standards. Additionally, the official Oreo FAQ mentions that their products are not certified as Kosher or Vegan, which could indicate potential issues for Halal status due to cross-contamination or use of non-Halal ingredients in certain flavors.

Source: Oreo Ingredients and Oreo FAQ

And Allah knows best.