CVE-2026-45352

Beschreibung

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.43.4, negative chunk-size in chunked Transfer-Encoding causes unbounded memory allocation and process crash. The ChunkedDecoder::read_payload function in cpp-httplib (httplib.h) parses the chunk-size field of HTTP chunked transfer encoding using std::strtoul(). Per the C standard (§7.22.1.4), strtoul silently accepts a leading minus sign, performing unsigned wrap-around: strtoul(--2-, …, 16) returns ULONG_MAX − 1 (0xFFFFFFFFFFFFFFFE). The library-s only guard (line 12833) rejects ULONG_MAX (the result of --1-), but any other negative value such as --2- passes validation. The resulting near-maximum value is stored in chunk_remaining and controls how many bytes the server-s read loop consumes from the network. This vulnerability is fixed in 0.43.4.