High severity · published Mar 27, 2026
CVE-2026-33745
cpp-httplib Client Leaks Authentication Credentials to Untrusted Hosts on Cross-Origin HTTP Redirect
7.4
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 19% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CP
cpp-httplib · yhirose
< 0.39.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33745
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33745
Exploit
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-6hrp-7fq9-3qv2
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