CVE-2026-33745

cpp-httplib Client Leaks Authentication Credentials to Untrusted Hosts on Cross-Origin HTTP Redirect

Published Mar 27, 2026 CVSS 3.1 · 7.4 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Yhirose
Yhirose cpp-httplib
Vendors & Products Yhirose
Yhirose cpp-httplib
Type Values Removed Values Added
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.
Title cpp-httplib Client Leaks Authentication Credentials to Untrusted Hosts on Cross-Origin HTTP Redirect
Weaknesses CWE-200
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Apr 1, 2026, 3:55 AM
Reserved
Mar 23, 2026, 5:34 PM
Status
Analyzed
Published
Mar 27, 2026, 1:16 AM
Modified
Jun 17, 2026, 10:38 AM