decoder_context::decode_slice_unit_tiles (libde265/decctx.cc:920) reads pps.CtbAddrRStoTS[ctbAddrRS] at line 966 where ctbAddrRS = ctbY * ctbsWidth + ctbX is computed from PPS-supplied colBd[]/rowBd[] arrays without validating the result against CtbAddrRStoTS.size() == sps->PicSizeInCtbsY. A malformed PPS that passes set_derived_values but encodes geometry inconsistent with the SPS produces a ctbAddrRS past the allocation, causing a 4-byte heap-buffer-overflow READ.