External risk intelligence

Apache DataSketches C++ CPC Sketch Deserialization Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-103513

Apache DataSketches C++ is a software library used for data processing and aggregation rather than a standalone network service or appliance. While the vulnerability occurs during deserialization, exploitation requires an application to actively ingest and deserialize untrusted data. Public internet exposure is uncommon for this type of component, as it typically functions as an internal library within data pipelines.

Out-of-bounds Read

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory addresses a critical vulnerability within the Apache DataSketches C++ library. The issue stems from how the library deserializes certain data, potentially allowing for memory corruption that could lead to application crashes and further exploitation. While the library is used in data processing, the risk is primarily limited to applications that deserialize data from untrusted sources.

Data corruption risk in a data processing library.
Matters if untrusted data is deserialized.
Confirm relevance and exposure for internal data handling.

Attack Path

How an attacker could exploit the issue

An attacker could potentially compromise systems by sending a specially crafted serialized CPC sketch to an application that deserializes data from untrusted sources. This crafted data can trigger an out-of-bounds read and write within the CPC sketch deserialization process, leading to heap memory corruption. If successful, this corruption could cause the application to crash or allow for further exploitation.

Untrusted data input required.
Vulnerable deserialization function triggered.
Heap corruption and potential exploitation.

Live Threat

Current exploitation, exposure, and threat context

A crafted serialized CPC sketch, when deserialized from untrusted sources, could lead to reading past buffer boundaries or writing outside an internal heap buffer. This can corrupt heap memory, potentially causing a crash and enabling further exploitation when supported by the advisory.

Heap memory corruption.
Deserializing untrusted CPC sketches.
Application crash or further exploitation.

Operational Fix

Recommended remediation, mitigation, and detection steps

Real-world ownership for this vulnerability likely falls to teams managing applications that utilize the Apache DataSketches C++ library for processing untrusted data. This could include data engineering, platform, or application development teams responsible for those specific services. The initial practical step involves identifying all deployed instances of the affected library, confirming which are exposed to untrusted data sources, and assessing their criticality to determine the remediation priority and appropriate owner.

Own by application or data platform teams.
Verify deserialize of untrusted data.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is Apache DataSketches C++?

It is a specialized software library designed for high-performance data processing and aggregation. Developers use it to summarize massive datasets into compact sketches, which helps in analyzing large-scale information efficiently within complex data pipelines.

What does CVE-2026-103513 mean for memory safety?

This vulnerability involves Out-of-Bounds Read and Write weaknesses (CWE-125 and CWE-787). In plain terms, the library fails to properly check data boundaries during the deserialization process. This allows incoming data to read past intended limits or overwrite adjacent heap memory, which can lead to application crashes or potentially allow malicious code execution.

How is this vulnerability triggered?

An attacker must provide a specially crafted serialized CPC sketch to an application using the affected library. The bug does not trigger during standard operations; it specifically occurs when the library attempts to deserialize data from an untrusted source. If your application only processes data from internal, trusted origins, it is not susceptible to this specific trigger path.

Is my system at risk?

Halo Surface Signal notes that this library typically functions as an internal component rather than an internet-facing service. The primary risk is to applications that ingest and deserialize untrusted CPC sketch data. If your software uses this library but does not accept external inputs, the actual exposure is significantly lower than for systems exposed to public networks.

How do I start addressing this issue?

Begin by auditing your software inventory to identify applications that incorporate the Apache DataSketches C++ library. Confirm whether any of these services process data from untrusted sources. If you find such applications, prioritize upgrading them to version 5.3.0, which resolves the boundary validation errors responsible for the memory corruption.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.