CVE-2026-45352

NameCVE-2026-45352
Descriptioncpp-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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1138578

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
cpp-httplib (PTS)bookworm0.11.4+ds-1+deb12u1vulnerable
trixie (security), trixie0.18.7-1+deb13u1vulnerable
forky, sid0.41.0+ds-3vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
cpp-httplibsource(unstable)(unfixed)1138578

Notes

https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-h6wq-j5mv-f3q8

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