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

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.

Scores

EPSS (exploitation in 30 days)

0.27% · top 81% of all CVEs (5 Nov 2026)

CISA SSVC

Exploitation: poc · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.4.

Weakness

• CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (opens in a new tab)All about CWE-200 and its CVEs

Affected products

• yhirose · cpp-httplib

  • affected < 0.39.0

References (1)

• https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-6hrp-7fq9-3qv2 (opens in a new tab)x_refsource_CONFIRM

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-33745](https://trackcve.app/badge/CVE-2026-33745.svg)](https://trackcve.app/cve/CVE-2026-33745)

Record last updated 1 Apr 2026, 03:55 UTC.