Quick answers
- Is CVE-2026-103635 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-103635 being exploited in the wild.
- How severe is CVE-2026-103635?
- Informational severity, published 10 October 2026.
- Which products and versions are affected?
- Apache DataSketches C++ 3.1.0 through 5.2.0.
- Is there a fix for CVE-2026-103635?
- Yes: fixed in 5.3.0. Until then: Only applications that deserialize Theta sketches from untrusted sources are affected; applications that only process sketches from trusted internal sources are not at risk.</anigation> <parameter name="timeline">[{"kind":"disclosed","at":"2026-10-10"}] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-103635 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-103635?
- Check whether you run Apache DataSketches C++ at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 5.3.0
Only applications that deserialize Theta sketches from untrusted sources are affected; applications that only process sketches from trusted internal sources are not at risk.</anigation> <parameter name="timeline">[{"kind":"disclosed","at":"2026-10-10"}]
Technical details
The compact_theta_sketch::deserialize() and wrapped_compact_theta_sketch::wrap() functions read header fields before validating that the input buffer is sufficiently long. In the compressed format, a 32-bit integer overflow can defeat the size check, and two unvalidated header fields control decoding logic. A crafted input causes a read past the buffer boundary; in compressed cases, over-reads can be large and read bytes may be incorporated into the deserialized sketch, leaking adjacent heap memory.
Affected products
- Apache DataSketches C++ 3.1.0 through 5.2.0