Resource exhaustion in Yhirose Cpp-Httplib
CVE-2026-45352
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.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.005 (40.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 40.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Yhirose Cpp-Httplib — versions < 0.43.4
Weakness classification (CWE)
References
- github.com/yhirose/cpp-httplib/security/advisories/GHSA-h6wq-j5mv-f3q8 (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-45352?
- CVE-2026-45352 is a medium-severity vulnerability in Yhirose Cpp-Httplib, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2026-05-29.
- How severe is CVE-2026-45352?
- Medium severity. CVSS v3 base score is 5.3 out of 10.