An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Redhat_linux | — | No solution exists | Oct 16, 2026 | Oct 14, 2026 |
| Ubuntu | — | Upgrade libcurl3-nssUpgrade libcurl4 (Ubuntu Pro)Upgrade libcurl4-nss-dev (Ubuntu Pro)Upgrade libcurl4-openssl-devUpgrade libcurl4-nss-devUpgrade libcurl4t64Upgrade curlUpgrade libcurl3 (Ubuntu Pro)Upgrade libcurl3t64-gnutlsUpgrade libcurl4Upgrade libcurl3-gnutls (Ubuntu Pro)Upgrade libcurl4-openssl-dev (Ubuntu Pro)Upgrade curl (Ubuntu Pro)Upgrade libcurl4-gnutls-devUpgrade libcurl3-gnutlsUpgrade libcurl4-gnutls-dev (Ubuntu Pro)Upgrade libcurl3-nss (Ubuntu Pro) | Oct 14, 2026 | Oct 14, 2026 |
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