CVE-2026-86413

critical

When using an *ambient user* in a first transfer doing Negotiate authentication and asked to follow redirects, curl could pass on its credential details to an…

When using an *ambient user* in a first transfer doing Negotiate authentication and asked to follow redirects, curl could pass on its credential details to an unrelated second origin when asked to redirect there.

CVSS

9.1

9.1 (CVSS v3.1)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Severity source: NVD CVSS v3.1 (134c704f-9b21-4f2e-91b3-4a467353bcc0)

Timeline (UTC)

Published: 2026-10-20 20:17

Modified: 2026-10-30 12:16

NVD status: Awaiting Analysis

Last synced 1 day ago

Verified against the source API 2026-11-03 07:34 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

Not reported by the source (unknown — not "none").

Weakness classification (CWE)

CWE-201

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

No vendor advisory or patch reference tagged by NVD. Check the references below.

References

https://curl.se/docs/CVE-2026-86413.html 2499f714-1537-4658-8207-48ae4bb9eae9
https://curl.se/docs/CVE-2026-86413.json 2499f714-1537-4658-8207-48ae4bb9eae9
https://hackerone.com/reports/3993549 2499f714-1537-4658-8207-48ae4bb9eae9
https://hackerone.com/reports/3993549 134c704f-9b21-4f2e-91b3-4a467353bcc0

Data sources

NVD CVE API 2.0 — fetched 2026-11-03 07:34 UTC · record ↗

Learn the basics

Understanding CVEs and CVSS Scores