# What is CVE-2020-1938?

> CVE-2020-1938 is a critical-severity flaw (CVSS 9.8) in Tomcat from Apache, published on 24 February 2020. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at over 99%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2020-1938

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **Precursor Intelligence risk score:** 89 out of 100 (Critical); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** Critical (CVSS 9.8 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** over 99% (latest exploit-likelihood forecast)
- **Published:** 24 February 2020
- **Record last updated:** 27 October 2025
- **Main product:** Tomcat from Apache
- **Affected products:** 21

## What is CVE-2020-1938? In plain terms

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The official description

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.

### What kind of flaw is it?

- Unknown: Unknown

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Easy: no special conditions
- Login needed first: No login needed
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

Severity vector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Is CVE-2020-1938 being exploited? Yes

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at over 99%.

Exploit likelihood over the last 7 days: >99%, >99%, >99%, >99%, >99%, >99%, >99%.

### Timeline

- 24 February 2020: Published
- 27 October 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2020-1938 scores **89 out of 100 (Critical)**, with the action "Emergency patch".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2020-1938?

The published record lists 21 products. Versions are as published: "7.0.0 to before 7.0.100" means from 7.0.0 up to, but not including, 7.0.100.

- [Tomcat](https://www.precursorintelligence.com/product/apache/tomcat) by [Apache](https://www.precursorintelligence.com/vendors/apache) (Application): 7.0.0 to before 7.0.100, 8.5.0 to before 8.5.51, 9.0.0 to before 9.0.31
- [Workspaces Server](https://www.precursorintelligence.com/product/blackberry/workspaces_server) by [Blackberry](https://www.precursorintelligence.com/vendors/blackberry) (Application): 7.0.1, 7.1.2, 8.1.0, 9.0
- [Agile Plm](https://www.precursorintelligence.com/product/oracle/agile_plm) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 9.3.3, 9.3.5, 9.3.6
- [Communications Element Manager](https://www.precursorintelligence.com/product/oracle/communications_element_manager) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 8.1.1, 8.2.0, 8.2.1
- [Debian Linux](https://www.precursorintelligence.com/product/debian/debian_linux) by [Debian](https://www.precursorintelligence.com/vendors/debian) (Operating system): 8.0, 9.0, 10.0
- [Fedora](https://www.precursorintelligence.com/product/fedoraproject/fedora) by [Fedoraproject](https://www.precursorintelligence.com/vendors/fedoraproject) (Operating system): 30, 31, 32
- [Workload Manager](https://www.precursorintelligence.com/product/oracle/workload_manager) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 12.2.0.1, 18c, 19c
- [Hospitality Guest Access](https://www.precursorintelligence.com/product/oracle/hospitality_guest_access) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 4.2.0, 4.2.1
- [Mysql Enterprise Monitor](https://www.precursorintelligence.com/product/oracle/mysql_enterprise_monitor) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): up to 4.0.12, 8.0.0 to 8.0.20
- [Agile Engineering Data Management](https://www.precursorintelligence.com/product/oracle/agile_engineering_data_management) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 6.2.1.0
- [Communications Instant Messaging Server](https://www.precursorintelligence.com/product/oracle/communications_instant_messaging_server) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 10.0.1.4.0
- [Data Availability Services](https://www.precursorintelligence.com/product/netapp/data_availability_services) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Application): version not specified
- [Geode](https://www.precursorintelligence.com/product/apache/geode) by [Apache](https://www.precursorintelligence.com/vendors/apache) (Application): 1.12.0
- [Good Control](https://www.precursorintelligence.com/product/blackberry/good_control) by [Blackberry](https://www.precursorintelligence.com/vendors/blackberry) (Application): up to 5.2.58.38
- [Health Sciences Empirica Inspections](https://www.precursorintelligence.com/product/oracle/health_sciences_empirica_inspections) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 1.0.1.2
- [Health Sciences Empirica Signal](https://www.precursorintelligence.com/product/oracle/health_sciences_empirica_signal) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 7.3.3
- [Instantis Enterprisetrack](https://www.precursorintelligence.com/product/oracle/instantis_enterprisetrack) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 17.1 to 17.3
- [Leap](https://www.precursorintelligence.com/product/opensuse/leap) by [Opensuse](https://www.precursorintelligence.com/vendors/opensuse) (Operating system): 15.1
- [Oncommand System Manager](https://www.precursorintelligence.com/product/netapp/oncommand_system_manager) by [Netapp](https://www.precursorintelligence.com/vendors/netapp) (Application): 3.0.0 to 3.1.3
- [Siebel UI Framework](https://www.precursorintelligence.com/product/oracle/siebel_ui_framework) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): up to 20.5
- [Transportation Management](https://www.precursorintelligence.com/product/oracle/transportation_management) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 6.3.7

## How do I fix CVE-2020-1938?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [lists.apache.org](https://lists.apache.org/thread.html/r9f119d9ce9239114022e13dbfe385b3de7c972f24f05d6dbd35c1a2f%40%3Cusers.tomcat.apache.org%3E) (Mailing list, Patch)
- [lists.apache.org](https://lists.apache.org/thread.html/rb1c0fb105ce2b93b7ec6fc1b77dd208022621a91c12d1f580813cfed%40%3Cdev.tomcat.apache.org%3E) (Mailing list, Patch)
- [lists.apache.org](https://lists.apache.org/thread.html/rd0774c95699d5aeb5e16e9a600fb2ea296e81175e30a62094e27e3e7%40%3Ccommits.ofbiz.apache.org%3E) (Mailing list, Patch)
- [oracle.com](https://www.oracle.com/security-alerts/cpujan2021.html) (Patch, Third-party advisory)
- [oracle.com](https://www.oracle.com/security-alerts/cpujul2020.html) (Patch, Third-party advisory)
- [lists.apache.org](https://lists.apache.org/thread.html/r7c6f492fbd39af34a68681dbbba0468490ff1a97a1bd79c6a53610ef%40%3Cannounce.tomcat.apache.org%3E) (Mailing list, Vendor advisory)
- [lists.apache.org](https://lists.apache.org/thread.html/r8f7484589454638af527182ae55ef5b628ba00c05c5b11887c922fb1%40%3Cnotifications.ofbiz.apache.org%3E) (Mailing list, Vendor advisory)
- [lists.apache.org](https://lists.apache.org/thread.html/r90890afea72a9571d666820b2fe5942a0a5f86be406fa31da3dd0922%40%3Cannounce.apache.org%3E) (Mailing list, Vendor advisory)
- [lists.apache.org](https://lists.apache.org/thread.html/ra7092f7492569b39b04ec0decf52628ba86c51f15efb38f5853e2760%40%3Cnotifications.ofbiz.apache.org%3E) (Mailing list, Vendor advisory)
- [lists.apache.org](https://lists.apache.org/thread.html/rf1bbc0ea4a9f014cf94df9a12a6477d24a27f52741dbc87f2fd52ff2%40%3Cissues.geode.apache.org%3E) (Mailing list, Vendor advisory)
- [lists.apache.org](https://lists.apache.org/thread.html/rf992c5adf376294af31378a70aa8a158388a41d7039668821be28df3%40%3Ccommits.tomee.apache.org%3E) (Mailing list, Vendor advisory)
- [lists.opensuse.org](http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00025.html) (Third-party advisory)
- [lists.opensuse.org](http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00002.html) (Mailing list, Third-party advisory)
- [support.blackberry.com](http://support.blackberry.com/kb/articleDetail?articleNumber=000062739) (Third-party advisory)
- [lists.apache.org](https://lists.apache.org/thread.html/r089dc67c0358a1556dd279c762c74f32d7a254a54836b7ee2d839d8e%40%3Cdev.tomee.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r1125f3044a0946d1e7e6f125a6170b58d413ebd4a95157e4608041c7%40%3Cannounce.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r17aaa3a05b5b7fe9075613dd0c681efa60a4f8c8fbad152c61371b6e%40%3Cusers.tomcat.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r38a5b7943b9a62ecb853acc22ef08ff586a7b3c66e08f949f0396ab1%40%3Cusers.tomcat.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r43faacf64570b1d9a4bada407a5af3b2738b0c007b905f1b6b608c65%40%3Cusers.tomcat.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r47caef01f663106c2bb81d116b8380d62beac9e543dd3f3bc2c2beda%40%3Ccommits.tomee.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r4afa11e0464408e68f0e9560e90b185749363a66398b1491254f7864%40%3Cusers.tomcat.apache.org%3E) (Issue tracking, Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r4f86cb260196e5cfcbbe782822c225ddcc70f54560f14a8f11c6926f%40%3Cusers.tomcat.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r549b43509e387a42656f0641fa311bf27c127c244fe02007d5b8d6f6%40%3Cdev.tomcat.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r57f5e4ced436ace518a9e222fabe27fb785f09f5bf974814cc48ca97%40%3Ccommits.tomee.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r5e2f1201b92ee05a0527cfc076a81ea0c270be299b87895c0ddbe02b%40%3Cusers.tomcat.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r61f280a76902b594692f0b24a1dbf647bb5a4c197b9395e9a6796e7c%40%3Cusers.tomcat.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r6a5633cad1b560a1e51f5b425f02918bdf30e090fdf18c5f7c2617eb%40%3Ccommits.tomee.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r74328b178f9f37fe759dffbc9c1f2793e66d79d7a8a20d3836551794%40%3Cnotifications.ofbiz.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r75113652e46c4dee687236510649acfb70d2c63e074152049c3f399d%40%3Cnotifications.ofbiz.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r772335e6851ad33ddb076218fa4ff70de1bf398d5b43e2ddf0130e5d%40%3Cdev.tomcat.apache.org%3E) (Issue tracking, Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r856cdd87eda7af40b50278d6de80ee4b42d63adeb433a34a7bdaf9db%40%3Cnotifications.ofbiz.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/r92d78655c068d0bc991d1edbdfb24f9c5134603e647cade1113d4e0a%40%3Cusers.tomee.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/rad36ec6a1ffc9e43266b030c22ceeea569243555d34fb4187ff08522%40%3Cnotifications.ofbiz.apache.org%3E) (Exploit, Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/rb2fc890bef23cbc7f343900005fe1edd3b091cf18dada455580258f9%40%3Cusers.tomcat.apache.org%3E) (Issue tracking, Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/rbdb1d2b651a3728f0ceba9e0853575b6f90296a94a71836a15f7364a%40%3Cdev.tomee.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/rc068e824654c4b8bd4f2490bec869e29edbfcd5dfe02d47cbf7433b2%40%3Cdev.tomee.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/rcd5cd301e9e7e39f939baf2f5d58704750be07a5e2d3393e40ca7194%40%3Ccommits.tomee.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/rce2af55f6e144ffcdc025f997eddceb315dfbc0b230e3d750a7f7425%40%3Cnotifications.ofbiz.apache.org%3E) (Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/rd50baccd1bbb96c2327d5a8caa25a49692b3d68d96915bd1cfbb9f8b%40%3Cusers.tomcat.apache.org%3E) (Issue tracking, Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/re5eecbe5bf967439bafeeaa85987b3a43f0e6efe06b6976ee768cde2%40%3Cusers.tomcat.apache.org%3E) (Issue tracking, Mailing list)
- [lists.apache.org](https://lists.apache.org/thread.html/rf26663f42e7f1a1d1cac732469fb5e92c89908a48b61ec546dbb79ca%40%3Cbugs.httpd.apache.org%3E) (Mailing list)
- [lists.debian.org](https://lists.debian.org/debian-lts-announce/2020/03/msg00006.html) (Third-party advisory)
- [lists.debian.org](https://lists.debian.org/debian-lts-announce/2020/05/msg00026.html) (Third-party advisory)
- [lists.fedoraproject.org](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2XFLQB3O5QVP4ZBIPVIXBEZV7F2R7ZMS/) (Release notes)
- [lists.fedoraproject.org](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K3IPNHCKFVUKSHDTM45UL4Q765EHHTFG/) (Release notes)
- [lists.fedoraproject.org](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L46WJIV6UV3FWA5O5YEY6XLA73RYD53B/) (Release notes)
- [security.gentoo.org](https://security.gentoo.org/glsa/202003-43) (Third-party advisory)
- [security.netapp.com](https://security.netapp.com/advisory/ntap-20200226-0002/) (Third-party advisory)
- [debian.org](https://www.debian.org/security/2020/dsa-4673) (Third-party advisory)
- [debian.org](https://www.debian.org/security/2020/dsa-4680) (Third-party advisory)

## Questions

### What is CVE-2020-1938?

CVE-2020-1938 is a critical-severity flaw in Tomcat from Apache, published on 24 February 2020. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2020-1938?

It scores 9.8 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2020-1938 is 89 out of 100, which is Critical. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

### Is CVE-2020-1938 being exploited?

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at over 99%.

### Which versions does CVE-2020-1938 affect?

For Tomcat from Apache: 7.0.0 to before 7.0.100, 8.5.0 to before 8.5.51, 9.0.0 to before 9.0.31. The record lists 21 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2020-1938?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.

## Does CVE-2020-1938 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

Start free (no card, nothing to install): https://www.precursorintelligence.com/register
Book a demo: https://www.precursorintelligence.com/contact