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Fencer Intel
medium —

CVE-2026-123274 json

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

published 2d ago modified 2d ago also EUVD-2026-125275

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

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.

Patch / fix

Is CVE-2026-123274 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-14).

Affected products

  • Apache Software Foundation Apache DataSketches C++

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.