CVE-2026-86414

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:`.

EPSS

0.2% chance of exploitation in the next 30 days; higher than 12% of CVEs (scores of 2026-10-25)

Published

2026-10-20

Modified

2026-10-22

Record from

the NVD, synced 2026-10-23

References

• https://curl.se/docs/CVE-2026-86414.html
• https://curl.se/docs/CVE-2026-86414.json
• https://hackerone.com/reports/3993566

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