---
id: CVE-2026-103634
title: >-
  Apache DataSketches: datasketches-cpp: Out-of-bounds read and write in
  Count-Min sketch deserialization allows memory corruption via a crafted sketch
summary: >-
  Out-of-bounds read and write in the Count-Min sketch deserialization of Apache
  DataSketches C++ (repo: datasketches-cpp).


  count_min_sketch::deserialize() did not include the preamble in its input size
  check, so a truncated sketch could …
severity: none
cwe:
  - CWE-787
  - CWE-190
vendor: Apache Software Foundation
product: apache/datasketches-cpp
affected:
  - apache/datasketches-cpp >= 4.1.0 <= 5.2.0
published: '2026-10-22'
updated: '2026-10-22'
sourceUpdated: '2026-10-22T07:16:57.732Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-103634'
references:
  - url: 'https://lists.apache.org/thread/rkx9oh06g5cjc6vmmpqloxwfz0gzz01h'
  - url: 'https://github.com/apache/datasketches-cpp/releases/tag/5.3.0'
tags:
  - cve.org
ingestedAt: '2026-10-22T07:32:31.139Z'
---

## Overview

Out-of-bounds read and write in the Count-Min sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp).

count_min_sketch::deserialize() did not include the preamble in its input size check, so a truncated sketch could cause a read of up to 16 bytes past the end of the input. In addition, the table size was computed from the serialized number of buckets and number of hash functions in 32-bit arithmetic. A crafted sketch could make it wrap to zero, so that the sketch deserialized with an empty table, and later updates and estimate queries read and wrote outside the heap allocation. This can corrupt heap memory, causing a crash and potentially enabling further exploitation.

This issue affects Apache DataSketches C++: from 4.1.0 before 5.3.0. Only applications that deserialize Count-Min sketches from untrusted sources are affected.

Users are recommended to upgrade to version 5.3.0, which fixes this issue.

## Affected

- `apache/datasketches-cpp >= 4.1.0 <= 5.2.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.