Emperor Wuzong died in 846 and was succeeded by his uncle
Emperor Xuānzong. In 852, with agrarian rebels occupying Mount Ji (雞山, in modern
Nanchong,
Sichuan), Emperor Xuānzong dispatched the general Wang Zhihong () to the region to deal with them. Cui suggested that instead an imperial official be sent to persuade them to submit, so Emperor Xuānzong sent the official Liu Tong (), who was able to persuade the Mount Ji rebels to surrender. (However, after Liu accepted their surrender, Wang and the eunuch monitor Sixian Yiyi () slaughtered the surrendered rebels anyway.) In 855, with Huainan Circuit (淮南, headquartered in modern
Yangzhou,
Jiangsu) suffering from a famine, but the military governor
Du Cong not governing the circuit diligently, Emperor Xuānzong removed Du from the post and sent Cui out to Huainan to serve as its military governor, continuing to carry the
Tong Zhongshu Menxia Pingzhangshi title as an honorary title. He was also created the greater title of Duke of Wei. As he departed for Huainan, Emperor Xuānzong held a great feast to send him off and personally wrote a poem to him. In 858, when the Xuanshe Circuit (宣歙, headquartered in modern
Xuancheng,
Anhui) officer Kang Quantai () mutinied and expelled the governor Zheng Xun (), who fled to Huainan's capital Yang Prefecture (), Cui launched his troops to attack the Xuanshe rebels, so Emperor Xuānzong gave him the additional title of governor of Xuanshe. Later in the year, he captured Xuanshe's capital Xuan Prefecture (), killing Kang and his coconspirators. He then resigned the additional post of governor of Xuanshe, which was then given to Wen Zhang (). == During Emperor Yizong's reign ==