The active imperfect is يَخَافُ; the passive is يُخَافُ. The imperfect prefixes have different vowels in the active and passive paradigms.
PronounActive imperfectPassive imperfect
هُوَيَخَافُيُخَافُ
هُمَا (م)يَخَافَانِيُخَافَانِ
هُمْيَخَافُونَيُخَافُونَ
هِيَتَخَافُتُخَافُ
هُمَا (ف)تَخَافَانِتُخَافَانِ
هُنَّيَخَفْنَيُخَفْنَ
أَنْتَتَخَافُتُخَافُ
The feminine-plural يَخَفْنَ contracts the medial long vowel before nūn al-niswah. Its corresponding passive is يُخَفْنَ.