CVE-2026-33745: cpp-httplib Client Leaks Authentication Credentials to Untrusted Hosts on Cross-Origin HTTP Redirect
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.39.0, the cpp-httplib HTTP client forwards stored Basic Auth, Bearer Token, and Digest Auth credentials to arbitrary hosts when following cross-origin HTTP redirects (301/302/307/308). A malicious or compromised server can redirect the client to an attacker-controlled host, which then receives the plaintext credentials in the Authorization header. Version 0.39.0 fixes the issue.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33745?
CVE-2026-33745 is considered a moderate severity vulnerability due to the potential exposure of sensitive authentication credentials.
How do I fix CVE-2026-33745?
To fix CVE-2026-33745, upgrade cpp-httplib to version 0.39.0 or later.
What types of credentials are leaked by CVE-2026-33745?
CVE-2026-33745 leaks Basic Auth, Bearer Token, and Digest Auth credentials to untrusted hosts on cross-origin HTTP redirects.
What impact does CVE-2026-33745 have on application security?
CVE-2026-33745 can lead to unauthorized access if authentication credentials are inadvertently sent to malicious servers.
Is my application vulnerable to CVE-2026-33745?
If you are using cpp-httplib version prior to 0.39.0, your application is vulnerable to CVE-2026-33745.