NULL pointer dereference in Yhirose Cpp-Httplib
CVE-2026-46527
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_proxies() with a non-empty trusted-proxy list, an attacker can send an HTTP request that includes an X-Forwarded-For header whose value parses to no valid IP segments. The code path then executes get_client_ip(), which calls front() on an empty std::vector—undefined behavior in C++. On typical implementations this manifests as abnormal process termination (denial of service). With Sanitizers enabled, you get an explicit runtime diagnostic. This vulnerability is fixed in 0.44.0.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (40.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.6% 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 < 0.44.0
Weakness classification (CWE)
References
- github.com/yhirose/cpp-httplib/security/advisories/GHSA-hg3g-vrg8-578g (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-46527?
- CVE-2026-46527 is a high-severity vulnerability in Yhirose Cpp-Httplib, classified under NULL Pointer Dereference. CVSS score: 7.5/10. Published 2026-05-29.
- How severe is CVE-2026-46527?
- High severity. CVSS v3 base score is 7.5 out of 10.