CVE-2026-46527: CWE-476: NULL Pointer Dereference in yhirose cpp-httplib
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.
AI Analysis
Technical Summary
The cpp-httplib library before version 0.44.0 has a vulnerability (CWE-476) where, if Server::set_trusted_proxies() is called with a non-empty list, an attacker can send an HTTP request with an X-Forwarded-For header containing invalid IP data. This triggers get_client_ip() to call front() on an empty std::vector, causing undefined behavior and usually a crash (denial of service). Sanitizers provide explicit runtime diagnostics for this. The vulnerability is resolved in version 0.44.0.
Potential Impact
An attacker can cause the cpp-httplib server to crash by sending a specially crafted HTTP request with an invalid X-Forwarded-For header when trusted proxies are configured. This results in denial of service due to abnormal process termination. There is no indication of privilege escalation, data disclosure, or code execution from the provided data.
Mitigation Recommendations
Upgrade cpp-httplib to version 0.44.0 or later where this vulnerability is fixed. No other mitigation or temporary workaround is indicated in the available data.
CVE-2026-46527: CWE-476: NULL Pointer Dereference in yhirose cpp-httplib
Description
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.
CVSS v4.0
Score 8.7high
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The cpp-httplib library before version 0.44.0 has a vulnerability (CWE-476) where, if Server::set_trusted_proxies() is called with a non-empty list, an attacker can send an HTTP request with an X-Forwarded-For header containing invalid IP data. This triggers get_client_ip() to call front() on an empty std::vector, causing undefined behavior and usually a crash (denial of service). Sanitizers provide explicit runtime diagnostics for this. The vulnerability is resolved in version 0.44.0.
Potential Impact
An attacker can cause the cpp-httplib server to crash by sending a specially crafted HTTP request with an invalid X-Forwarded-For header when trusted proxies are configured. This results in denial of service due to abnormal process termination. There is no indication of privilege escalation, data disclosure, or code execution from the provided data.
Mitigation Recommendations
Upgrade cpp-httplib to version 0.44.0 or later where this vulnerability is fixed. No other mitigation or temporary workaround is indicated in the available data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-14T19:12:32.755Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
- Gcve Source
- db.gcve.eu
Threat ID: 6a19feb2e29bf47b500fc27c
Added to database: 5/29/2026, 9:01:38 PM
Last enriched: 5/29/2026, 9:03:21 PM
Last updated: 5/31/2026, 4:41:28 AM
Views: 4
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