CVE-2026-103636: Apache DataSketches: datasketches-cpp: Out-of-bounds read in VarOpt union deserialization allows denial of service via a truncated sketch
Apache DataSketches C++ has a low-severity out-of-bounds read in VarOpt union deserialization that can crash on truncated input.
Apache DataSketches C++ versions 2.0.0-incubating through 5.2.0 are affected by CVE-2026-103636, an out-of-bounds read in var_opt_union::deserialize(). After checking that only 8 bytes are available, the function reads a 32-byte preamble, so a truncated serialized union can read up to 24 bytes past the end of the input. Apache rated the flaw low severity. The described impact is denial of service, and no exploitation is reported.
- CVE-2026-103636 is an out-of-bounds read in VarOpt union deserialization.
- Affected releases are DataSketches C++ 2.0.0-incubating through 5.2.0.
- A truncated sketch can read up to 24 bytes past the input.
- Apache rated the issue low; impact is denial of service.
- CVEs
- CVE-2026-103636
- Vendors
- Apache Software Foundation
- Organizations
- Apache Software Foundation
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-103636 | Out-of-bounds read in Apache DataSketches C++ VarOpt unions | 7.5 | — |
From the original article
Posted by Lee Rhodes on Oct 10 Severity: low Affected versions: - Apache DataSketches 2. 0. 0-incubating through 5.
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