How broadly exploitable is this vulnerability?

Exploitability depends on how the deployment uses `forward_auth` and which headers are trusted downstream. If downstream services treat forwarded headers as authoritative identity or role indicators, any client who can reach the Caddy instance and craft HTTP headers may be able to exploit the issue.

Does an attacker need prior authentication or special access?

Not necessarily. The attacker primarily needs network access to the affected Caddy endpoint and knowledge or guesswork about which headers are trusted by downstream services. In many configurations, this can be achieved without pre-existing credentials.

What is the safest general fix pattern?

Ensure that identity and authorization headers are generated and controlled exclusively by the authentication component or proxy, not by clients. Strip all client-supplied versions of these headers and have the proxy explicitly set them based on verified authentication results, overwriting any incoming values.

Severity:

HIGH RISK

(8.1)

Improper Authentication via Header Injection (CWE-287) in Caddy forward_auth copy_headers

CVE-2026-30851

Published:

Mar 7, 2026

Status:

Received

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

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Vulnerability Type

Category:

Improper Authentication / Identity Injection

CWE:

CWE-287;CWE-345

Impact:

Authentication Bypass and Privilege Escalation via Trust of Spoofed Identity Headers

Severity:

HIGH RISK

(8.1)

CVSS Version:

3.1

Vulnerability Type

Category:

Improper Authentication / Identity Injection

CWE:

CWE-287;CWE-345

Impact:

Authentication Bypass and Privilege Escalation via Trust of Spoofed Identity Headers

Severity:

HIGH RISK

(8.1)

CVSS Version:

3.1

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Ask AI for summary of CodeAnt

Improper Authentication via Header Injection (CWE-287) in Caddy forward_auth copy_headers

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

CRITICAL RISK

CRITICAL

(9.9)

Command Injection in MCP Stdio Configuration Validation (CWE-78) in WeKnora

CRITICAL RISK

CRITICAL

(9.9)

SQL Injection via PostgreSQL Array/Row Expressions (CWE-89) in WeKnora Query Engine

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

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