Your RSA-2048 keys break in 2030. Find every one of them before attackers do.

CVE-2007-4556

CVE-2007-4556 is a remote code execution vulnerability in opensymphony xwork. O3 Security detects and blocks CVE-2007-4556 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.

Struts support in OpenSymphony XWork before 1.2.3, and 2.x before 2.0.4, as used in WebWork and Apache Struts, recursively evaluates all input as an Object-Graph Navigation Language…

Published
Aug 28, 2007
Updated
Jun 16, 2026
Affected
0 pkgs
Patched
None yet
Exploits
None indexed

Description

Struts support in OpenSymphony XWork before 1.2.3, and 2.x before 2.0.4, as used in WebWork and Apache Struts, recursively evaluates all input as an Object-Graph Navigation Language (OGNL) expression when altSyntax is enabled, which allows remote attackers to cause a denial of service (infinite loop) or execute arbitrary code via form input beginning with a "%{" sequence and ending with a "}" character.

Affected Products

1 product · 2 configurations
Application
xworkopensymphony
≥ 2.0.0 && ≤ 2.0.4
range

Detection & mitigation playbook

Vendor / appliance
  1. Detect

    Inventory every opensymphony xwork 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 remote code execution at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

  2. Fix

    Apply the opensymphony xwork security patch or hotfix for CVE-2007-4556 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    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.

  4. How O3 protects you

    O3 detects and blocks CVE-2007-4556 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-2007-4556. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Struts support in OpenSymphony XWork before 1.2.3, and 2.x before 2.0.4, as used in WebWork and Apache Struts, recursively evaluates all input as an Object-Graph Navigation Language (OGNL) expression when altSyntax is enabled, which allows remote attackers to cause a denial of service (infinite loop) or execute arbitrary code via form input beginning with a "%{" sequence and ending with a "}" character.
O3 Security · Runtime Protection

Is CVE-2007-4556 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2007-4556 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.