CVE-2011-2526
CVE-2011-2526 is a Improper Input Validation vulnerability in apache tomcat. O3 Security detects and blocks CVE-2011-2526 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.
Apache Tomcat 5.5.x before 5.5.34, 6.x before 6.0.33, and 7.x before 7.0.19, when sendfile is enabled for the HTTP APR or HTTP NIO connector, does not validate certain request attributes,…
Description
Apache Tomcat 5.5.x before 5.5.34, 6.x before 6.0.33, and 7.x before 7.0.19, when sendfile is enabled for the HTTP APR or HTTP NIO connector, does not validate certain request attributes, which allows local users to bypass intended file access restrictions or cause a denial of service (infinite loop or JVM crash) by leveraging an untrusted web application.
Affected Products
tomcatapacheDetection & mitigation playbook
Vendor / applianceDetect
Inventory every apache tomcat 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-2011-2526 yet — track the apache tomcat 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-2011-2526 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-2011-2526. 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-2011-2526 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2011-2526 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.