CVE-2026-33745 cpp-httplib Client Leaks Authentication Credentials to Untrusted Hosts on Cross-Origin HTTP Redirect
The cpp-httplib client leaks authentication credentials to untrusted hosts during cross-origin redirects, allowing attackers to steal sensitive data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33745?
CVE-2026-33745 is a high-severity vulnerability in yhirose cpp-httplib, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-200
Which versions are affected by CVE-2026-33745?
It affects 1 product.
Products include Yhirose Cpp-Httplib.
How do I fix CVE-2026-33745?
Upgrade to a fixed version.
Is CVE-2026-33745 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33745 exists.
Other vulnerabilities in yhirose cpp-httplib
- CVE-2025-66570 cpp-httplib Untrusted HTTP Header Handling: Internal Header Shadowing (REMOTE*/LOCAL*)
- CVE-2026-45372 cpp-httplib: HTTP header value percent-decoding in server-side `parse_header` enables CRLF injection
- CVE-2026-46527 Null dereference in cpp-httplib
- CVE-2026-32627 cpp-httplib has a Silent TLS Certificate Verification Bypass on HTTPS Redirect via Proxy
- CVE-2026-22776 cpp-httplib vulnerable to a denial of service (DOS) using a zip bomb
Sources
Also known as DEBIAN-CVE-2026-33745, GHSA-6hrp-7fq9-3qv2, UBUNTU-CVE-2026-33745.