# CVE-2026-33745: cpp-httplib: cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library

CVE-2026-33745 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-33745, released March 27, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-33745
- Priority: High
- CVSS: 7.4 (high)
- EPSS: 0.0027
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 27, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | cpp-httplib Debian 14 | 0.41.0+ds-3 | [DEBIAN-CVE-2026-33745](https://patchblox.com/security/data/fix/linux/debian-cve-2026-33745.md) | Mar 27, 2026 |
| Linux | cpp-httplib Fedora 43 | 0.48.0-1.fc43 | [FEDORA-2026-1D4BD0354A](https://patchblox.com/security/data/fix/linux/fedora-2026-1d4bd0354a.md) | Jun 24, 2026 |
| Linux | cpp-httplib-devel Fedora 43 | 0.48.0-1.fc43 | [FEDORA-2026-1D4BD0354A](https://patchblox.com/security/data/fix/linux/fedora-2026-1d4bd0354a.md) | Jun 24, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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