CVE-2026-45352 - cpp-httplib DoS: Negative chunk-size in chunked Transfer-Encoding

CVE-2026-45352 - cpp-httplib DoS: Negative chunk-size in chunked Transfer-Encoding

https://cvefeed.io/rssfeed/latest.atom / Fri, 05/29/2026 - 23:26
CVE ID :CVE-2026-45352
Published : May 29, 2026, 8:16 p.m. | 45 minutes ago
Description :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.
Severity: 5.3 | MEDIUM
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