CVE-2020-9484

NameCVE-2020-9484
DescriptionWhen 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDLA-2209-1, DLA-2217-1, DLA-2279-1, DSA-4727-1
NVD severitymedium
Debian Bugs961209

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
tomcat7 (PTS)stretch7.0.75-1vulnerable
tomcat8 (PTS)stretch8.5.54-0+deb9u1vulnerable
stretch (security)8.5.54-0+deb9u4fixed
tomcat9 (PTS)buster, buster (security)9.0.31-1~deb10u2fixed
bullseye, sid9.0.39-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
tomcat7sourcejessie7.0.56-3+really7.0.100-1+deb8u1DLA-2217-1
tomcat7source(unstable)(unfixed)
tomcat8sourcejessie8.0.14-1+deb8u17DLA-2209-1
tomcat8sourcestretch8.5.54-0+deb9u2DLA-2279-1
tomcat8source(unstable)(unfixed)
tomcat9sourcebuster9.0.31-1~deb10u2DSA-4727-1
tomcat9source(unstable)9.0.35-1961209

Notes

[stretch] - tomcat7 <ignored> (No components in libservlet3.0-java binary package are affected)
https://github.com/apache/tomcat/commit/bb33048e3f9b4f2b70e4da2e6c4e34ca89023b1b (10.0.0-M5)
https://github.com/apache/tomcat/commit/3aa8f28db7efb311cdd1b6fe15a9cd3b167a2222 (9.0.35)
https://github.com/apache/tomcat/commit/ec08af18d0f9ddca3f2d800ef66fe7fd20afef2f (8.5.55)
https://github.com/apache/tomcat/commit/53e30390943c18fca0c9e57dbcc14f1c623cfd06 (7.0.104)

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