What is CVE-2026-8286?

CVE-2026-8286 is a high-severity vulnerability in Curl, classified under Improper Certificate Validation. CVSS score: 8.1/10. Published 2026-07-03.

How severe is CVE-2026-8286?

High severity. CVSS v3 base score is 8.1 out of 10.

Vulnerability in Curl

CVE-2026-8286

A vulnerability exists where a new transfer that uses STARTTLS to upgrade the connection might reuse an existing live connection even though the TLS configuration mismatches so it should not.

Vulnerability class: Improper Certificate Validation

Published 2026-07-03 · last modified 2026-09-15.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.003 (21.6th percentile), scored 2026-10-06.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 21.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Curl — versions 8.20.0, 8.19.0, 8.18.0
Haxx Curl

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

2499f714-1537-4658-8207-48ae4bb9eae9 (Vendor Advisory)
2499f714-1537-4658-8207-48ae4bb9eae9 (Patch, Vendor Advisory)
2499f714-1537-4658-8207-48ae4bb9eae9 (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2026-8286?: CVE-2026-8286 is a high-severity vulnerability in Curl, classified under Improper Certificate Validation. CVSS score: 8.1/10. Published 2026-07-03.
How severe is CVE-2026-8286?: High severity. CVSS v3 base score is 8.1 out of 10.