Description

CERT Polska has received a report about vulnerability in simdjson library and participated in coordination of its disclosure.

The vulnerability CVE-2026-8295: An integer overflow vulnerability in the simdjson document-builder API allows incorrect buffer size calculations in string_builder::escape_and_append() when processing very large input strings on platforms with limited size_t width (e.g., 32-bit builds). The overflow can cause insufficient buffer allocation, leading to out-of-bounds memory reads in SIMD routines and potentially resulting in information disclosure, memory corruption, or malformed JSON output.

This vulnerability has been fixed in release 4.6.4.

Credits

We thank Michał Majchrowicz and Marcin Wyczechowski from AFINE for the responsible vulnerability report.