WAF – WAF Release – 2025-10-13

This week’s highlights include a new JinJava rule targeting a sandbox-bypass flaw that could allow malicious template input to escape execution controls. The rule improves detection for unsafe template rendering paths.

Key Findings

New WAF rule deployed for JinJava (CVE-2025-59340) to block a sandbox bypass in the template engine that permits attacker-controlled type construction and arbitrary class instantiation; in vulnerable environments this can escalate to remote code execution and full server compromise.

Impact

• CVE-2025-59340 — Exploitation enables attacker-supplied type descriptors / Jackson ObjectMapper abuse, allowing arbitrary class loading, file/URL access (LFI/SSRF primitives) and, with suitable gadget chains, potential remote code execution and system compromise.

Ruleset	Rule ID	Legacy Rule ID	Description	Previous Action	New Action	Comments
Cloudflare Managed Ruleset	b327d6442e2d4848b4aab3cbc04bab5f	100892	JinJava – SSTI – CVE:CVE-2025-59340	Log	Block	This is a New Detection

Source: Cloudflare

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