# CVE-2026-123274: Apache DataSketches C++: Out-of-bounds write in KLL sketch deserialization allows memory corruption via a crafted sketch

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: apache) — https://github.com/apache/datasketches-cpp/commit/bb86d439db494e3d362e54cc4f83481893974335
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: apache) — https://github.com/apache/datasketches-cpp/pull/568

## Affected products and versions

- Apache Software Foundation / Apache DataSketches C++ (apache/datasketches-cpp): ≥ 1.0.0-incubating; ≤ 5.3.0 (affected, semver). Source: CNA: apache

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://lists.apache.org/thread/t4rngyg9cbv1b42f1d0crgpgtpby0594 (CNA: apache; vendor-advisory)

- https://github.com/apache/datasketches-cpp/releases/tag/5.3.1 (CNA: apache; release-notes)

- https://github.com/apache/datasketches-cpp/commit/bb86d439db494e3d362e54cc4f83481893974335 (CNA: apache; patch)

- https://github.com/apache/datasketches-cpp/pull/568 (CNA: apache; patch)

- http://www.openwall.com/lists/oss-security/2026/11/13/1 (ADP: CVE)

- https://github.com/apache/datasketches-cpp/commit/bb86d439db494e3d362e54cc4f83481893974335 (security@apache.org)

- https://github.com/apache/datasketches-cpp/pull/568 (security@apache.org)

- https://github.com/apache/datasketches-cpp/releases/tag/5.3.1 (security@apache.org)

- https://lists.apache.org/thread/t4rngyg9cbv1b42f1d0crgpgtpby0594 (security@apache.org)

- http://www.openwall.com/lists/oss-security/2026/11/13/1 (af854a3a-2127-422b-91ae-364da2661108)

## Provenance

- CNA: apache: https://www.cve.org/CVERecord?id=CVE-2026-123274; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123274; retrieved 2026-11-13; source updated 2026-11-13

Revision: e8dd7569702fb933bbd9c0107b3253ea213e57d980505e80bc9e04382d314950

Canonical: https://y2.dev/cve/CVE-2026-123274

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