Caddy
CVE-2026-30851
HIGH
GHSA-7r4p-vjf4-gxv4
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate as low-privileged user
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DeliveryCraft request with malicious headers
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ExploitCaddy forward_auth forwards unstripped headers
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ExecutionBackend trusts injected identity
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ImpactAttacker gains elevated privileges
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication mechanism validation
MITRE ATT&CK
2 techniques across 2 tactics: Defense Evasion, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Caddy versions 2.10.0 through 2.11.1 with forward_auth directive enabled and copy_headers configuration active. Attacker must have valid authentication credentials to the Caddy instance. Backend service must trust identity headers passed through forward_auth without independent validation. |
| Impact | CVSS 8.1 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Public exploit/POC available. |
| Exploit ScenarioDerived | An attacker could exploit this vulnerability to compromise the affected system. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Caddy versions 2.10.0 through 2.11.1 fail to strip client-supplied headers in the forward_auth copy_headers directive, enabling authenticated attackers to inject identity headers and escalate privileges. This authentication bypass vulnerability affects deployments relying on Caddy for request forwarding and has public exploit code available. The vulnerability requires valid authentication credentials but allows complete privilege elevation within affected systems.
Earlier versions of this analysis (1)
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. [CVSS 8.1 HIGH]
RemediationAI
A vendor patch is available — apply it immediately. Fixed in version 2.11.2.. Restrict network access to the affected service where possible.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 2 packages in go
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-287 (Improper Authentication). Affects Caddy. 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.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
Lifecycle Timeline
3DescriptionGitHub Advisory
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.
Executive ViewAI
Caddy versions 2.10.0 through 2.11.1 contain a critical authentication bypass vulnerability that could allow attackers to impersonate users and escalate privileges by injecting forged headers. Organizations using affected versions of Caddy as a reverse proxy or API gateway face immediate risk of unauthorized access to downstream applications and data.
Apply vendor patch. If immediate patching is not possible: disable the copy_headers directive in forward_auth configurations, implement WAF rules to strip or validate authentication-related headers at the perimeter, restrict network access to Caddy instances to trusted clients only, and enable detailed logging of all header modifications for forensic analysis.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.
Affected Products (CPE)GitHub Advisory
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Same weakness CWE-287 – Improper Authentication
View allSame technique Privilege Escalation
View allVendor StatusVendor
SUSE
Severity: High| Product | Status |
|---|---|
| openSUSE Leap 15.6 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP5 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP6 | Fixed |
| openSUSE Leap 15.5 | Fixed |
Exploit-DB