The BL Lacertae object S5 0716 + 714 is one of the most studied blazars on the sky due to its active variability and brightness in many bands , including VHE gamma rays . We present here two serendipitous results from recent far-ultraviolet spectroscopic observations by the Cosmic Origins Spectrograph onboard the Hubble Space Telescope . First , during the course of our 7.3 hour HST observations , the blazar increased in flux rapidly by \sim 40 % ( -0.45 { mag h ^ { -1 } } ) followed by a slower decline ( +0.36 { mag h ^ { -1 } } ) to previous far-UV flux levels . We model this flare using asymetric flare templates and constrain the physical size and energetics of the emitting region . Furthermore , the spectral index of the object softens considerably during the course of the flare from \alpha _ { \nu } \approx - 1.0 to \alpha _ { \nu } \approx - 1.4 . Second , we constrain the source redshift directly using the \sim 30 intervening absorption systems . A system at z = 0.2315 is detected in Ly \alpha , Ly \beta , O vi , and N v and defines the lower bound on the source redshift . No absorbers are seen in the remaining spectral coverage ( 0.2315 < z _ { Ly \alpha } \lesssim 0.47 ) and we set a statistical upper bound of z < 0.322 ( 95 % confidence ) on the blazar . This is the first direct redshift limit for this object and is consistent with literature estimates of z = 0.31 \pm 0.08 based on the detection of a host galaxy .