CVE-2024-21499Network attack vector

Security-control bypass via unvalidated redirect protocol

Published Feb 17, 2024 · Updated Aug 1, 2024

HTTP header injection in Greenpau Caddy Security 1.1.23 and earlier allows remote attackers to redirect users via X-Forwarded-Proto. The redirect logic trusts the client-controlled header without restricting it to accepted schemes and uses its value as the redirect protocol. The resulting redirect requires user interaction and can confuse TLS handling or bypass security controls; no stronger consequence is documented.

CVSS severity4.3
Medium
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP header injection in Greenpau Caddy Security 1.1.23 and earlier allows remote attackers to redirect users via X-Forwarded-Proto. The redirect logic trusts the client-controlled header without restricting it to accepted schemes and uses its value as the redirect protocol. The resulting redirect requires user interaction and can confuse TLS handling or bypass security controls; no stronger consequence is documented.

The record

CVE
CVE-2024-21499
Published
Feb 17, 2024
Updated
Aug 1, 2024
Vendor
Greenpau
Product
Caddy Security
Classifications
CWE-644, CWE-116
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 17, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 1, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Greenpau · Caddy Securityversion=0 <*

Published CVSS scores

4.3SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
4.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-644Improper Neutralization of HTTP Headers for Scripting Syntax
CWE-116Improper Encoding or Escaping of Output

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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