CVE-2020-9484

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.

How to fix CVE-2020-9484

To remediate CVE-2020-9484, upgrade the affected package to a fixed version below.

• —upgrade to 7.0.108 or later
• —upgrade to 7.0.56-3+really7.0.100-1+deb8u1 or later
• —upgrade to 9.0.35-1 or later
• —upgrade to 10.0.0-M5 or later
• —upgrade to 10.0.0-M5 or later

Is CVE-2020-9484 being exploited?

Likely — EPSS is 93.5%, placing CVE-2020-9484 in the top tier of vulnerabilities by exploitation probability. Prioritise patching.

Affected packages (5)

• >= 7.0.0, < 7.0.108, >= 8.5.0, < 8.5.63, >= 9.0.1, < 9.0.43
• from 0, < 7.0.56-3+really7.0.100-1+deb8u1
• from 0, < 9.0.35-1
• >= 10.0.0-M1, < 10.0.0-M5
• >= 10.0.0-M1, < 10.0.0-M5

CVSS scores

References (79)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2020-9484
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2020-9484
• PATCHgithub.com/apache/tomcat
• WEBlists.opensuse.org/opensuse-security-announce/2020-05/msg00057.html