CVE-2026-103634: out-of-bounds read and write in Count-Min sketch deserialization

According to the advisory published by Lee Rhodes on October 10, 2026 on the oss-sec feed, this moderate-severity flaw affects Apache DataSketches from version 4.1.0 through 5.2.0, in the datasketches-cpp repository. The problem lies in count_min_sketch::deserialize(), which did not include the preamble in the input size check. With a truncated sketch, the read can extend up to 16 bytes past the end of the input. The advisory also indicates that the table size was calculated from a value that the available text does not fully detail. The received content is an automatic translation and was cut off before the end, so this summary is limited to the data provided. To review the full analysis, the fix list and the project guidance, consult the original advisory cited in the oss-sec feed itself. To check your exposure, confirm the Apache DataSketches version in your environments and compare it with the affected range.