CVE-2026-103634
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk15th percentile - higher than 15% of all known CVEs
Summary
An out-of-bounds read and write in the Count-Min sketch deserialization of Apache DataSketches C++ (versions 4.1.0 to 5.3.0) occurs because the input size check did not include the preamble, allowing a truncated sketch to cause a read past the end. Additionally, the table size is computed in 32-bit arithmetic, which can wrap to zero, leading to an empty table and subsequent out-of-bounds reads and writes, corrupting heap memory.
Risk Assessment
Applications that deserialize Count-Min sketches from untrusted sources may experience memory corruption, crashes, and potentially enable further exploitation. This could lead to denial of service or code execution.
Recommendation
Upgrade Apache DataSketches C++ to version 5.3.0 or later. Avoid deserializing sketches from untrusted sources.
Other vulnerabilities in Apache DataSketches C++
See all- CVE-2026-103635Critical
Out-of-bounds read in the compact Theta sketch deserialization of Apache DataSketches C++ (datasketches-cpp). compact_theta_sketch::deserialize() and wrapped_compact_theta_sketch::wrap() read header fields before checking input length; in the compressed format the size check could be defeated by a 32-bit overflow. A crafted or truncated sketch could cause a read past the end of the input, potentially large in the compressed case, leading to a crash and memory exposure. Affects versions from 3.1.0 before 5.3.0.
- CVE-2026-103513Critical
Out-of-bounds read and write in the CPC sketch deserialization of Apache DataSketches C++ (datasketches-cpp). A crafted serialized CPC sketch passed to cpc_sketch::deserialize() can cause the decompressor to read past the end of compressed data, and in the hybrid flavor can cause a write outside an internal heap buffer due to unvalidated decoded row indices. This can corrupt heap memory, causing a crash and potentially enabling further exploitation. Affects versions from 2.0.0-incubating before 5.3.0.
- CVE-2026-103501Critical
Heap buffer overflow in the HLL sketch deserialization of Apache DataSketches C++ (datasketches-cpp). When deserializing a sketch in LIST mode, the coupon count was read from input and used as the number of entries to copy into a fixed buffer of 8 entries without checking capacity. A crafted sketch could cause a write of up to 988 bytes past the end of the internal heap buffer, corrupting memory. Affects versions from 1.0.0-incubating before 5.3.0.
- CVE-2026-103636High
Out-of-bounds read in the VarOpt union deserialization of Apache DataSketches C++ (datasketches-cpp). var_opt_union::deserialize() read the 32-byte preamble after checking only 8 bytes were available, so a truncated serialized union could cause a read of up to 24 bytes past the end of the input. This can cause a crash (denial of service) and could expose adjacent memory contents. Affects versions from 2.0.0-incubating before 5.3.0.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS