Vulnerability · Published Oct 10, 2026 · Assigned by apache
CVE-2026-103635Apache DataSketches: datasketches-cpp: Out-of-bounds read in compact Theta sketch deserialization allows denial of service via a crafted sketch
Critical 9.1
In plain English
A critical-severity out-of-bounds read in Apache DataSketches from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities).
Official description
Out-of-bounds read in the compact Theta sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp). compact_theta_sketch::deserialize() and wrapped_compact_theta_sketch::wrap() read header fields before checking that the input was long enough. For the compressed format, the size check could be defeated by a 32-bit overflow, and two header fields that control decoding were not validated; this also affected deserialization from a stream. A crafted or truncated sketch could cause a read past the end of the input. In the compressed case the over-read can be large, and the bytes read can become part of the deserialized sketch. This can cause a crash (denial of service) and could expose adjacent memory contents. This issue affects Apache DataSketches C++: from 3.1.0 before 5.3.0. Only applications that deserialize Theta sketches from untrusted sources are affected. Users are recommended to upgrade to version 5.3.0, which fixes this issue.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Apache Software Foundation | Apache DataSketches | 3.1.0 – through 5.2.0 |
Weakness: CWE-125, CWE-190 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H