CVE-2026-103634 Out-of-bounds read and write in the Count-Min sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp).
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-103634?
CVE-2026-103634 is a medium-severity vulnerability in Apache DataSketches, published on 22 Oct 2026.
Official description
Out-of-bounds read and write in the Count-Min sketch deserialization of Apache DataSketches C++ (repo: datasketches-cpp).
count_min_sketch::deserialize() did not include the preamble in its input size check, so a truncated sketch could cause a read of up to 16 bytes past the end of the input. In addition, the table size was computed from the serialized number of buckets and number of hash functions in 32-bit arithmetic. A crafted sketch could make it wrap to zero, so that the sketch deserialized with an empty table, and later updates and estimate queries read and wrote outside the heap allocation. This can corrupt heap memory, causing a crash and potentially enabling further exploitation.
This issue affects Apache DataSketches C++: from 4.1.0 before 5.3.0. Only applications that deserialize Count-Min 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-2026-103634?
How do I fix CVE-2026-103634?
No fix has been published for CVE-2026-103634 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-103634 being exploited?
There is no known exploitation of CVE-2026-103634 in the wild and no public exploit code.
Sources
Also known as GHSA-8255-5x7v-6cgv.