How severe is CVE-2020-9484?

CVE-2020-9484 has a CVSS score of 7/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-9484?

CVE-2020-9484 affects the following packages: org.apache.tomcat:tomcat-catalina (Maven), org.apache.tomcat:tomcat-catalina (Maven), org.apache.tomcat:tomcat-catalina (Maven), org.apache.tomcat:tomcat-catalina (Maven), org.apache.tomcat.embed:tomcat-embed-core (Maven), org.apache.tomcat.embed:tomcat-embed-core (Maven), org.apache.tomcat.embed:tomcat-embed-core (Maven), org.apache.tomcat.embed:tomcat-embed-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2020-9484?

Update org.apache.tomcat:tomcat-catalina to version 10.0.0-M5 or later. Run your dependency manager's update command and verify no transitive dependencies pin the vulnerable version. Use O3 Security's SCA scanner to confirm the fix is applied across your entire dependency tree.

Is CVE-2020-9484 actively exploited in the wild?

Yes. There are 28 known exploit references for CVE-2020-9484, including 15 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-9484?

CVE-2020-9484 has an EPSS (Exploit Prediction Scoring System) score of 93.5%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is there exploit tooling available for CVE-2020-9484?

A Nuclei detection template exists for CVE-2020-9484, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2020-9484 published, and has it been updated?

CVE-2020-9484 was published on May 20, 2020 and was last updated on April 16, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

CVE-2020-9484

HIGH

Potential remote code execution in Apache Tomcat

Also known asBIT-tomcat-2020-9484GHSA-344f-f5vg-2jfj

Published

May 20, 2020

Updated

Apr 16, 2026

Affected

8 pkgs

Patched

8 / 8

Exploits

28 known

EPSS Exploitation Probability

via FIRST.org ↗

93.5%probability of exploitation in next 30 days

Very High Risk100th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

8 pkgs affected

☕org.apache.tomcat:tomcat-catalina☕org.apache.tomcat:tomcat-catalina☕org.apache.tomcat:tomcat-catalina☕org.apache.tomcat:tomcat-catalina☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

When using Apache Tomcat versions 10.0.0-M1 to 10.0.0-M4, 9.0.0.M1 to 9.0.34, 8.5.0 to 8.5.54 and 7.0.0 to 7.0.103 if a) an attacker is able to control the contents and name of a file on the server; and b) the server is configured to use the PersistenceManager with a FileStore; and c) the PersistenceManager is configured with sessionAttributeValueClassNameFilter="null" (the default unless a SecurityManager is used) or a sufficiently lax filter to allow the attacker provided object to be deserialized; and d) the attacker knows the relative file path from the storage location used by FileStore to the file the attacker has control over; then, using a specifically crafted request, the attacker will be able to trigger remote code execution via deserialization of the file under their control. Note that all of conditions a) to d) must be true for the attack to succeed.

Affected Packages

8 total 8 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.tomcat:tomcat-catalina`	≥ 10.0.0-M1&&< 10.0.0-M5	10.0.0-M5
☕Maven	`org.apache.tomcat:tomcat-catalina`	≥ 9.0.0&&< 9.0.35	9.0.35
☕Maven	`org.apache.tomcat:tomcat-catalina`	≥ 8.0.0&&< 8.5.55	8.5.55
☕Maven	`org.apache.tomcat:tomcat-catalina`	≥ 7.0.0&&< 7.0.104	7.0.104
☕Maven	`org.apache.tomcat.embed:tomcat-embed-core`	≥ 10.0.0-M1&&< 10.0.0-M5	10.0.0-M5
☕Maven	`org.apache.tomcat.embed:tomcat-embed-core`	≥ 9.0.0&&< 9.0.35	9.0.35

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.