Actively exploited in the wild
Apache Tomcat Improper Privilege Management Vulnerability
Apache - Tomcat · Listed in the CISA KEV since 2022-03-03. This indicates confirmed attacks in production environments.
Required action: Apply updates per vendor instructions.
CVE-2020-1938
CriticalCVSS 9.8KEVExploitation Probability (EPSS)
Very high risk100th percentile - higher than 100% of all known CVEs
Summary
The Ghostcat vulnerability in Apache Tomcat affects the AJP protocol. The default-enabled AJP connector listened on all IP addresses, allowing an attacker to read arbitrary files from the web application and process them as JSP, potentially leading to remote code execution.
Risk Assessment
The risk to the organization includes unauthorized access to sensitive application files and potential server compromise if the application allows file uploads or the attacker can control file content.
Recommendation
Immediately disable the AJP connector if not required, or upgrade Tomcat to versions 9.0.31, 8.5.51, or 7.0.100 and later. Also restrict access to the AJP port to trusted networks only.
Other vulnerabilities in Apache Tomcat
See all- CVE-2025-48989High
A vulnerability in Apache Tomcat related to improper resource shutdown or release allows for a 'made you reset' attack. This affects versions from 11.0.0-M1 to 11.0.9, from 10.1.0-M1 to 10.1.43, and from 9.0.0.M1 to 9.0.107.
- CVE-2017-7675High
The HTTP/2 implementation in Apache Tomcat from version 9.0.0.M1 to 9.0.0.M21 and from 8.5.0 to 8.5.15 bypassed several security checks that prevented directory traversal attacks. It was therefore possible to bypass security constraints using a specially crafted URL.
- CVE-2016-6817High
The HTTP/2 header parser in Apache Tomcat versions 9.0.0.M1 to 9.0.0.M11 and 8.5.0 to 8.5.6 entered an infinite loop if a header larger than the available buffer was received. This made a denial of service attack possible.
- CVE-2017-5650High
In Apache Tomcat versions 9.0.0.M1 to 9.0.0.M18 and 8.5.0 to 8.5.12, the handling of an HTTP/2 GOAWAY frame did not close streams associated with that connection waiting for a WINDOW_UPDATE, potentially leading to exhaustion of available processing threads.
- CVE-2016-6816High
The code in Apache Tomcat versions from 6.0.0 to 9.0.0.M11 allowed parsing of the HTTP request line with invalid characters. This could be exploited in conjunction with a proxy that also accepted these characters to inject data into the HTTP response.
- CVE-2017-6056High
A programming error was discovered in the processing of HTTPS requests in the Apache Tomcat servlet and JSP engine, which may result in denial of service due to an infinite loop. This issue arises from backporting the CVE-2016-6816 fix without including the fix for Tomcat bug 57544.
- CVE-2026-103119Critical
A buffer under-read vulnerability in Apache Tomcat means a large non-blocking write could result in the response body being split between the current request and the next request on that connection, most likely causing failure of the second request and possible leakage of data from the first response to the second.
- CVE-2026-101356Critical
Incorrect object recycling and reuse in Apache Tomcat affecting HTTP/2 processing of asynchronous servlets can trigger request and/or response mix-up between users. Affects versions 11.0.22 through 11.0.26, 10.1.55 through 10.1.60, and 9.0.118 through 9.0.122.
- CVE-2026-101296Critical
A missing critical authentication step in Apache Tomcat when the JNDI realm was configured with a non-GSSAPI SASL authentication mechanism allowed attackers to authenticate without providing the correct password. Affects versions 11.0.0-M1 through 11.0.26, 10.1.0-M1 through 10.1.60, and 9.0.0.M1 through 9.0.122; EOL versions 8.5.0-8.5.100 and 7.0.0-7.0.109 are also known to be affected.
- CVE-2026-86350Critical
Inconsistent interpretation of HTTP/2 requests ('HTTP Request/Response smuggling') vulnerability in Apache Tomcat caused by a regression in fix for CVE-2026-41293 can trigger request header mix-up. This issue affects Apache Tomcat: from 11.0.22 through 11.0.25, from 10.1.55 through 10.1.59, from 9.0.118 through 9.0.121. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.
Original NVD description (English source)
When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat. Tomcat treats AJP connections as having higher trust than, for example, a similar HTTP connection. If such connections are available to an attacker, they can be exploited in ways that may be surprising. In Apache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99, Tomcat shipped with an AJP Connector enabled by default that listened on all configured IP addresses. It was expected (and recommended in the security guide) that this Connector would be disabled if not required. This vulnerability report identified a mechanism that allowed: - returning arbitrary files from anywhere in the web application - processing any file in the web application as a JSP Further, if the web application allowed file upload and stored those files within the web application (or the attacker was able to control the content of the web application by some other means) then this, along with the ability to process a file as a JSP, made remote code execution possible. It is important to note that mitigation is only required if an AJP port is accessible to untrusted users. Users wishing to take a defence-in-depth approach and block the vector that permits returning arbitrary files and execution as JSP may upgrade to Apache Tomcat 9.0.31, 8.5.51 or 7.0.100 or later. A number of changes were made to the default AJP Connector configuration in 9.0.31 to harden the default configuration. It is likely that users upgrading to 9.0.31, 8.5.51 or 7.0.100 or later will need to make small changes to their configurations.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS