Apache · Tomcat
CVE-2020-1938
Apache Tomcat Improper Privilege Management Vulnerability
What it is
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.
CISA: Apache Tomcat treats Apache JServ Protocol (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.
What to do
Apply updates per vendor instructions.
Deadline for US federal agencies: March 17, 2022
- Added to the CISA list
- March 3, 2022
- Published
- February 24, 2020
- Severity
- Critical 9.8 CVSS 3.1
- Chance of attacks in the next 30 days (EPSS)
- 99.3% in the top 0.1% of all known vulnerabilities
- More details
- NVD · CVE.org · CISA
All references (20)
- https://lists.apache.org/thread.html/r7c6f492fbd39af34a68681dbbba0468490ff1a97a1bd79c6a53610ef%40%3Cannounce.…
- https://lists.apache.org/thread.html/r856cdd87eda7af40b50278d6de80ee4b42d63adeb433a34a7bdaf9db%40%3Cnotificat…
- https://lists.apache.org/thread.html/r75113652e46c4dee687236510649acfb70d2c63e074152049c3f399d%40%3Cnotificat…
- https://lists.apache.org/thread.html/rd0774c95699d5aeb5e16e9a600fb2ea296e81175e30a62094e27e3e7%40%3Ccommits.o…
- https://lists.apache.org/thread.html/r74328b178f9f37fe759dffbc9c1f2793e66d79d7a8a20d3836551794%40%3Cnotificat…
- https://lists.apache.org/thread.html/rce2af55f6e144ffcdc025f997eddceb315dfbc0b230e3d750a7f7425%40%3Cnotificat…
- https://lists.apache.org/thread.html/rad36ec6a1ffc9e43266b030c22ceeea569243555d34fb4187ff08522%40%3Cnotificat…
- https://lists.apache.org/thread.html/rb2fc890bef23cbc7f343900005fe1edd3b091cf18dada455580258f9%40%3Cusers.tom…
- https://lists.apache.org/thread.html/r38a5b7943b9a62ecb853acc22ef08ff586a7b3c66e08f949f0396ab1%40%3Cusers.tom…
- https://lists.apache.org/thread.html/r17aaa3a05b5b7fe9075613dd0c681efa60a4f8c8fbad152c61371b6e%40%3Cusers.tom…
- https://lists.apache.org/thread.html/rd50baccd1bbb96c2327d5a8caa25a49692b3d68d96915bd1cfbb9f8b%40%3Cusers.tom…
- https://lists.apache.org/thread.html/r4afa11e0464408e68f0e9560e90b185749363a66398b1491254f7864%40%3Cusers.tom…
- https://lists.apache.org/thread.html/r772335e6851ad33ddb076218fa4ff70de1bf398d5b43e2ddf0130e5d%40%3Cdev.tomca…
- https://lists.debian.org/debian-lts-announce/2020/03/msg00006.html
- https://lists.apache.org/thread.html/re5eecbe5bf967439bafeeaa85987b3a43f0e6efe06b6976ee768cde2%40%3Cusers.tom…
- https://lists.apache.org/thread.html/r5e2f1201b92ee05a0527cfc076a81ea0c270be299b87895c0ddbe02b%40%3Cusers.tom…
- https://lists.apache.org/thread.html/r549b43509e387a42656f0641fa311bf27c127c244fe02007d5b8d6f6%40%3Cdev.tomca…
- https://lists.apache.org/thread.html/r61f280a76902b594692f0b24a1dbf647bb5a4c197b9395e9a6796e7c%40%3Cusers.tom…
- https://lists.apache.org/thread.html/r4f86cb260196e5cfcbbe782822c225ddcc70f54560f14a8f11c6926f%40%3Cusers.tom…
- https://lists.apache.org/thread.html/r9f119d9ce9239114022e13dbfe385b3de7c972f24f05d6dbd35c1a2f%40%3Cusers.tom…
More exploited flaws from Apache
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Aug 4, 2026 | Missing Encryption of Sensitive Data | Tomcat | High 7.5 | 99% |
| Apr 1, 2025 | Path Equivalence | Tomcat | Critical 10.0 | 99.9% |
| May 12, 2023 | Remote Code Execution | Tomcat | Critical 9.8 | 90% |
| Mar 25, 2022 | on Windows Remote Code Execution | Tomcat | High 8.1 | 99.7% |
| Mar 25, 2022 | Remote Code Execution | Tomcat | High 8.1 | >99.9% |
| Oct 8, 2026 | Command Injection | Struts | High 8.1 | 97% |
| Apr 16, 2026 | Improper Input Validation | ActiveMQ | High 8.8 | 98% |
| May 1, 2025 | Improper Escaping of Output | HTTP Server | Critical 9.1 | >99.9% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.