CVE-2026-27586 is a critical vulnerability affecting Caddy server versions prior to 2.11.1. It allows for silent failure of mTLS client certificate authentication when a CA certificate file is missing or malformed, causing the server to accept any system-trusted client certificate instead of the intended private CA. This vulnerability has a CVSS score of 9.1 (Critical), indicating a network-exploitable flaw with low attack complexity and high impact on confidentiality and integrity. While there is no known active exploitation or public exploit code, the vulnerability has garnered some community discussion, as evidenced by its higher-than-average mentions.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 2.11.1CPE matchmatch criteria | cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:* |
CVSS version used by this source: 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.
The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.