Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Yhirose | Cpp-Httplib | < 0.43.4 |
Related Weaknesses (CWE)
References
- https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-h6wq-j5mv-f3q8ExploitVendor Advisory
- https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-h6wq-j5mv-f3q8ExploitVendor Advisory
FAQ
What is CVE-2026-45352?
CVE-2026-45352 is a vulnerability with a CVSS score of 5.3 (MEDIUM). 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...
How severe is CVE-2026-45352?
CVE-2026-45352 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-45352?
Check the references section above for vendor advisories and patch information. Affected products include: Yhirose Cpp-Httplib.