New firmware builds have been certified for the Sony Xperia M (C1904, C1905) and Xperia M dual (C2004, C2005). These new firmware versions are likely to be Android 4.3 builds and are incremental revisions over the previously certified versions. The Xperia M has moved from build number 15.4.A.0.21 to 15.4.A.0.23, whilst the Xperia M dual has moved from build number 15.5.A.0.16 to 15.5.A.0.18. We will keep you posted if and when these firmware builds go live.
Thanks ?@KaneshiroAngga!