---
id: "CVE-2026-123274"
page: "https://infrastack.ai/live/CVE-2026-123274"
kind: "vulnerability"
aliases: ["CVE-2026-123274"]
title: "Apache DataSketches C++: crafted KLL sketch corrupts heap memory on load"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "Apache DataSketches C++", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["apache-datasketches", "c++", "data-processing", "package"]
not_affected_if: ["no-kll-deserialization", "trusted-input-only"]
published_at: "2026-11-13T11:17:16+00:00"
first_seen_at: "2026-11-13T11:44:16+00:00"
updated_at: "2026-11-13T11:44:34+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123274", "first_seen_at": "2026-11-13T11:44:16+00:00"}]
exploit_sources: []
---

# Apache DataSketches C++: crafted KLL sketch corrupts heap memory on load

Link for people: https://infrastack.ai/live/CVE-2026-123274 (this .md is for agents)

Apache DataSketches C++ does not validate level boundaries when it deserializes a KLL sketch. A crafted sketch from an untrusted source can overwrite heap memory in the application that loads it.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Apache DataSketches C++ affected range not listed fixed no fixed version listed

## How to check

- Check the installed version of Apache DataSketches C++ against the affected range `2.0.0` through `5.3.0`.
- Search your code for calls that deserialize KLL sketches from data you do not control, such as network input or uploaded files.

## Fix

- Apache DataSketches C++: upgrade to `5.3.1`.

## Timeline

- 2026-11-13T11:44:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123274

## Documents

- [fix] Patch: github.com https://github.com/apache/datasketches-cpp/commit/bb86d439db494e3d362e54cc4f83481893974335
- [fix] Release notes: github.com https://github.com/apache/datasketches-cpp/releases/tag/5.3.1

## From the sources

Out-of-bounds Write vulnerability in Apache DataSketches C++. An
  application that deserializes a KLL sketch from an untrusted source
  can have heap memory corrupted by a crafted sketch, because the
  serialized level boundaries were not validated.

  This issue affects Apache DataSketches C++: 2.0.0 through 5.3.0.

  Users are recommended to upgrade to version 5.3.1, which fixes the
  issue.

---

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