CVE-2026-86411

CRITICAL
INFO Priority: 0.01 BB Relevance: 78/100
Published: 2026-10-20 Modified: 2026-10-29 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Auth No Interaction Conf. Impact Integ. Impact

CVSS Vector Breakdown

AV: Network
AC: Low
PR: None
UI: None
S: Unchanged
C: High
I: High
A: None

Description

An `ftp://` transfer configured with `CURLUSESSL_NONE` can reuse a pooled FTP control connection that a previous easy handle upgraded with `STARTTLS` and authenticated using a client certificate. The second handle performs neither a new TLS handshake nor a new FTP login, so the server continues to authorize it under the first handle's certificate identity.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
curl curl 8.21.0

Bug Bounty Relevance

78 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity
✓ No user interaction

CVSS Score

9.1 / 10.0 v3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploitation Probability

0.15%
Raw Score 0.001530
Percentile 4.4%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00153
2026-10-28
0.00153

Intelligence Sources

mitre ref →
nvd ref →