CVE-2026-87866
criticalWhen built with wolfSSL, curl can successfully validate a pinned public key hash against a key the TLS peer does not possess.
When built with wolfSSL, curl can successfully validate a pinned public key hash against a key the TLS peer does not possess. During the TLS handshake, wolfSSL validates the connection, but curl's subsequent re-parsing of the same certificate - tricked by a manipulated validity length field - extracts and matches a different embedded key, incorrectly authorizing the pinned public key.
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 21:17
Modified: 2026-10-29 19:17
NVD status: Awaiting Analysis
Last synced 5 days ago
Verified against the source API 2026-10-30 08:34 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)
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-2026-87866.html 2499f714-1537-4658-8207-48ae4bb9eae9
- https://curl.se/docs/CVE-2026-87866.json 2499f714-1537-4658-8207-48ae4bb9eae9
- https://hackerone.com/reports/3989514 2499f714-1537-4658-8207-48ae4bb9eae9
- https://hackerone.com/reports/3989514 134c704f-9b21-4f2e-91b3-4a467353bcc0
Data sources
NVD CVE API 2.0 — fetched 2026-10-30 08:34 UTC · record ↗