CVE-2026-103635 Memory corruption in Apache DataSketches
Crafted Theta sketches cause out-of-bounds reads in Apache DataSketches C++, leading to crashes or memory exposure during deserialization.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-103635?
CVE-2026-103635 is a critical memory corruption vulnerability in Apache DataSketches, published on 10 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-103635?
How do I fix CVE-2026-103635?
No fix has been published for CVE-2026-103635 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-103635 being exploited?
There is no known exploitation of CVE-2026-103635 in the wild and no public exploit code.
Sources
Also known as GHSA-hh2m-8j82-33gp.