CVE-2011-2526

CVE-2011-2526 is a medium-severity vulnerability in Apache Tomcat with a CVSS 2.0 base score of 4.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

• Severity: Medium (CVSS 2.0 base score 4.4)
• EPSS exploit prediction: 1% (49th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-20
• Affected product: Apache Tomcat
• Published: 2011-07-14
• Last modified: 2026-06-16

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.

Frequently asked questions

What is CVE-2011-2526?

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.

How severe is CVE-2011-2526?

CVE-2011-2526 has a CVSS 2.0 base score of 4.4, rated medium severity.

Is CVE-2011-2526 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-2526?

CVE-2011-2526 primarily affects Apache Tomcat. In total, 80 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2011-2526?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2011-2526 published?

CVE-2011-2526 was published on 2011-07-14 and last updated on 2026-06-16.

References

• http://marc.info/?l=bugtraq&m=132215163318824&w=2
• http://marc.info/?l=bugtraq&m=133469267822771&w=2
• http://marc.info/?l=bugtraq&m=136485229118404&w=2
• http://marc.info/?l=bugtraq&m=139344343412337&w=2
• http://osvdb.org/73797
• http://osvdb.org/73798
• http://rhn.redhat.com/errata/RHSA-2012-0074.html
• http://rhn.redhat.com/errata/RHSA-2012-0075.html
• http://rhn.redhat.com/errata/RHSA-2012-0076.html
• http://rhn.redhat.com/errata/RHSA-2012-0077.html
• http://rhn.redhat.com/errata/RHSA-2012-0078.html
• http://rhn.redhat.com/errata/RHSA-2012-0325.html
• http://secunia.com/advisories/45232
• http://secunia.com/advisories/48308
• http://secunia.com/advisories/57126
• http://svn.apache.org/viewvc?view=revision&revision=1145383
• http://svn.apache.org/viewvc?view=revision&revision=1145571
• http://svn.apache.org/viewvc?view=revision&revision=1145694
• http://svn.apache.org/viewvc?view=revision&revision=1146005
• http://tomcat.apache.org/security-5.html
• http://tomcat.apache.org/security-6.html
• http://tomcat.apache.org/security-7.html
• http://www.debian.org/security/2012/dsa-2401
• http://www.mandriva.com/security/advisories?name=MDVSA-2011:156
• http://www.securityfocus.com/archive/1/518889/100/0/threaded
• http://www.securityfocus.com/bid/48667
• http://www.securitytracker.com/id?1025788
• https://bugzilla.redhat.com/show_bug.cgi?id=720948
• https://exchange.xforce.ibmcloud.com/vulnerabilities/68541
• https://lists.apache.org/thread.html/06cfb634bc7bf37af7d8f760f118018746ad8efbd519c4b789ac9c2e%40%3Cdev.tomcat.apache.org%3E

Affected products (80)

• cpe:2.3:a:apache:tomcat:5.5.0:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.1:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.2:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.3:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.4:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.5:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.6:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.7:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.8:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.9:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.10:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.11:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.12:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.13:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.14:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.15:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.16:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.17:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.18:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.19:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.20:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.21:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.22:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.23:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.24:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.25:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.26:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.27:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.28:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.29:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.30:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.31:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.32:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:5.5.33:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:6.0:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:6.0.0:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:6.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:6.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:6.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:apache:tomcat:6.0.4:*:*:*:*:*:*:*

More vulnerabilities in Apache Tomcat

• CVE-2026-43512 — Critical (CVSS 9.8): DEPRECATED: Authentication Bypass Issues vulnerability in digest authentication in Apache Tomcat. This issue affects…
• CVE-2026-41293 — Critical (CVSS 9.8): Improper Input Validation vulnerability in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through…
• CVE-2025-31651 — Critical (CVSS 9.8): Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in Apache Tomcat. For a subset of unlikely…
• CVE-2025-24813 — Critical (CVSS 9.8): Path Equivalence: 'file.Name' (Internal Dot) leading to Remote Code Execution and/or Information disclosure and/or…
• CVE-2024-56337 — Critical (CVSS 9.8): Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in Apache Tomcat. This issue affects Apache Tomcat:…
• CVE-2024-50379 — Critical (CVSS 9.8): Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability during JSP compilation in Apache Tomcat permits an RCE…

All CVEs affecting Apache Tomcat →

Other CWE-20 (Improper Input Validation) vulnerabilities

• CVE-2026-48316 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
• CVE-2026-48281 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
• CVE-2026-48277 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
• CVE-2026-48055 — Critical (CVSS 10.0): Streambert is a cross-platform Electron Desktop App to stream and download any video media. In versions 2.4.0 and…
• CVE-2026-34910 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi OS…
• CVE-2026-33587 — Critical (CVSS 10.0): Lack of user input sanitisation in Open Notebook v1.8.3 allows the application user to execute Python code (and…

Browse all CWE-20 (Improper Input Validation) vulnerabilities →