CVE-2026-103635
Out-of-bounds read in the compact Theta sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp). compact_theta_sketch::deserialize() and wrapped_compact_theta_sketch::wrap() read header fields before checking that the input was long enough. For the compressed format, the size check could be defeated by a 32-bit overflow, and two header fields that control decoding were not validated; this also affected deserialization from a stream. A crafted or truncated sketch could cause a read past the end of the input. In the compressed case the over-read can be large, and the bytes read can become part of the deserialized sketch. This can cause a crash (denial of service) and could expose adjacent memory contents. This issue affects Apache DataSketches C++: from 3.1.0 before 5.3.0. Only applications that deserialize Theta sketches from untrusted sources are affected. Users are recommended to upgrade to version 5.3.0, which fixes this issue.
Executive briefing
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Severity & attack characteristics
CVSS vector:Not supplied
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Technical explanation & impact
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Affected products and versions
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Remediation & validation
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- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
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Vendor advisories, patches & exploit references
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