CVE-2024-21496
MEDIUMAll versions of the package github.com/greenpau/caddy-security are vulnerable to Cross-site Scripting (XSS) via the Referer header, due to improper input sanitization. Although the…
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Description
All versions of the package github.com/greenpau/caddy-security are vulnerable to Cross-site Scripting (XSS) via the Referer header, due to improper input sanitization. Although the Referer header is sanitized by escaping some characters that can allow XSS (e.g., [&], [<], [>], ["], [']), it does not account for the attack based on the JavaScript URL scheme (e.g., javascript:alert(document.domain)// payload). Exploiting this vulnerability may not be trivial, but it could lead to the execution of malicious scripts in the context of the target user’s browser, compromising user sessions.
Affected Products
caddy-securityauthcrunchDetection & mitigation playbook
Vendor / applianceDetect
Inventory every authcrunch caddy-security deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2024-21496 yet — track the authcrunch caddy-security advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2024-21496 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2024-21496. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-21496 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2024-21496 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.