Quick answers
- Is CVE-2026-103634 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-103634 being exploited in the wild.
- How severe is CVE-2026-103634?
- Informational severity, published 22 October 2026.
- Which products and versions are affected?
- Apache DataSketches C++ 4.1.0 through 5.2.0.
- Is there a fix for CVE-2026-103634?
- Yes: fixed in 5.3.0. Until then: Applications should only deserialize Count-Min sketches from trusted sources until upgrading to version 5.3.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-103634 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-103634?
- 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
Applications should only deserialize Count-Min sketches from trusted sources until upgrading to version 5.3.0.
Technical details
The count_min_sketch::deserialize() function fails to include the preamble in its input size check, allowing truncated sketches to read up to 16 bytes past the buffer end. Additionally, table size computation uses 32-bit arithmetic that can wrap to zero when given a crafted sketch, causing subsequent updates and queries to read and write outside heap allocation. The vulnerability affects only applications deserializing sketches from untrusted sources and is fixed in version 5.3.0.
Affected products
- Apache DataSketches C++ 4.1.0 through 5.2.0
Timeline
- 2026-10-22: disclosed: Public disclosure date based on NVD publication
- 2026-10-08: patched: Fixed in version 5.3.0 released on October 8, 2026