CVE-2026-30851: caddyserver caddy · Improper Authentication
Affects caddyserver caddySource CVE Database V5
Not known to be exploited · CVSS 8.1 High : upgrade to 2.11.2 soon.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.11.2
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 7 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade caddy and caddyserver/caddy to 2.11.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| caddyservercaddy | Affected
| Fixed in
|
GitHubcaddyserver/caddypkg:github/caddyserver/caddyOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
- Upgrade all affected Caddy servers to version 2.11.2 or later, where the vulnerability is patched.
- Review and audit configurations of the forward_auth module, specifically the copy_headers option, to ensure no client-supplied headers are trusted or forwarded without validation.
- Implement strict header sanitization and validation on all authentication-related headers at the proxy or application level.
- Employ network segmentation and access controls to limit exposure of Caddy servers to untrusted networks.
- Monitor logs for unusual authentication header patterns or unexpected privilege escalations.
- Consider deploying Web Application Firewalls (WAFs) with rules to detect and block suspicious header injection attempts.
- Educate development and operations teams about secure header handling practices to prevent similar issues in custom extensions or configurations.
- Conduct penetration testing focused on authentication bypass scenarios to validate the effectiveness of mitigations.
Description
Caddy is an extensible server platform that uses TLS by default. From version 2.10.0 to before version 2.11.2, forward_auth copy_headers does not strip client-supplied headers, allowing identity injection and privilege escalation. This issue has been patched in version 2.11.2.