My boss assumed I was at fault for a certain issue – in fact, it was my fellow worker’s fault. Am I allowed to clear my name by saying who was the person to blame? This is a case where there’s no danger of being fired for the issue, but the boss will likely think less of my work due to it.
You should say that it wasn’t you. Even if your boss will understand from this response that it was your fellow worker’s fault, it is still allowed (assuming that the issue is really a problem as it indeed seems from your question, and not an “imaginary” problem that your boss feels is an issue when in reality nothing wrong was done).
All the best
Chofetz Chaim Hilchos Lashon Hara 10:17, and Be’er Mayim Chaim 10:43