Vulnerability in Apache Software Foundation Apache DataSketches

[ Why it matters ]Priority signals

• Critical severity: CVSS 9.8

[ Description ]Official description

Heap buffer overflow in the HLL sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp). When deserializing a sketch in LIST mode, from either a byte buffer or a stream, the coupon count was read from the input and used as the number of entries to copy into a fixed buffer of 8 entries, without checking it against the buffer's capacity. A crafted sketch could cause a write of up to 988 bytes past the end of this internal heap buffer. This can corrupt heap memory, causing a crash and potentially enabling further exploitation. This issue affects Apache DataSketches C++: from 1.0.0-incubating before 5.3.0. Only applications that deserialize HLL sketches from untrusted sources are affected. Users are recommended to upgrade to version 5.3.0, which fixes this issue.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• github.com/apache/datasketches-cpp/releases/tag/5.3.0
• lists.apache.org/thread/n2oc2j841dzsv4239jjp08of66bo79c5
• www.openwall.com/lists/oss-security/2026/10/10/2