# CVE-2020-9484

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.

- Page: https://www.vulneraibility.com/cve/CVE-2020-9484
- CVSS: 7.0
- Known exploited: not in CISA KEV as of our last sync
- EPSS: 55.52% (percentile 99.0)
- Unvetted proof-of-concept code on GitHub: 17 GitHub proofs of concept · 1 Nuclei template (first 2020-05-19)
- CISA SSVC: exploitation none, automatable no, technical impact total (assessed 2026-10-08)
- Published: 2020-05-20

## Affected versions

- Apache Tomcat: affected Apache Tomcat 10.0.0-M1 to 10.0.0-M4, 9.0.0.M1 to 9.0.34, 8.5.0 to 8.5.54, 7.0.0 to 7.0.103

A version outside these ranges is not a statement that it is unaffected.

## References

- [other] https://lists.apache.org/thread.html/rf70f53af27e04869bdac18b1fc14a3ee529e59eb12292c8791a77926%40%3Cusers.tomcat.apache.org%3E
- [other] https://lists.debian.org/debian-lts-announce/2020/05/msg00020.html
- [other] https://lists.apache.org/thread.html/r26950738f4b4ca2d256597cf391d52d3450fa665c297ea5ca38f5469%40%3Cusers.tomcat.apache.org%3E
- [advisory] http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00057.html
- [other] https://lists.apache.org/thread.html/r7bc247fffcb1d58415215c861d2354bd653c86266230d78a93c71ae2%40%3Cdev.tomcat.apache.org%3E
- [other] https://lists.debian.org/debian-lts-announce/2020/05/msg00026.html
- [other] http://seclists.org/fulldisclosure/2020/Jun/6
- [advisory] https://security.gentoo.org/glsa/202006-21
- [advisory] https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WJ7XHKWJWDNWXUJH6UB7CLIW4TWOZ26N/
- [advisory] https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GIQHXENTLYUNOES4LXVNJ2NCUQQRF5VJ/
- [other] https://lists.apache.org/thread.html/rb1c0fb105ce2b93b7ec6fc1b77dd208022621a91c12d1f580813cfed%40%3Cdev.tomcat.apache.org%3E
- [other] https://lists.debian.org/debian-lts-announce/2020/07/msg00010.html
- [other] https://www.oracle.com/security-alerts/cpujul2020.html
- [other] https://lists.apache.org/thread.html/r77eae567ed829da9012cadb29af17f2df8fa23bf66faf88229857bb1%40%3Cannounce.tomcat.apache.org%3E
- [other] https://security.netapp.com/advisory/ntap-20200528-0005/
- [other] http://packetstormsecurity.com/files/157924/Apache-Tomcat-CVE-2020-9484-Proof-Of-Concept.html
- [advisory] https://www.debian.org/security/2020/dsa-4727
- [advisory] https://usn.ubuntu.com/4448-1/
- [other] https://lists.apache.org/thread.html/r123b3ebe389f46f9d337923f393cdae4d3e9b78d982d706712f0898c%40%3Ccommits.tomee.apache.org%3E
- [other] https://lists.apache.org/thread.html/raa4123e472175bb052fbba165d37187cea923f755e8f3f30d124cb3f%40%3Ccommits.tomee.apache.org%3E
- [other] https://lists.apache.org/thread.html/rc8473b08abdf3c16494ed817bec1717a0ee0c8080315bc27db5f21c3%40%3Ccommits.tomee.apache.org%3E
- [other] https://lists.apache.org/thread.html/rf59c72572b9fee674a5d5cc6afeca4ffc3918a02c354a81cc50b7119%40%3Ccommits.tomee.apache.org%3E
- [other] https://www.oracle.com/security-alerts/cpuoct2020.html
- [other] https://kc.mcafee.com/corporate/index?page=content&id=SB10332
- [advisory] https://usn.ubuntu.com/4596-1/
- [other] https://www.oracle.com/security-alerts/cpujan2021.html
- [other] https://lists.apache.org/thread.html/rfe62fbf9d4c314f166fe8c668e50e5d9dd882a99447f26f0367474bf%40%3Cdev.tomcat.apache.org%3E
- [other] https://lists.apache.org/thread.html/rfe62fbf9d4c314f166fe8c668e50e5d9dd882a99447f26f0367474bf%40%3Cannounce.apache.org%3E
- [other] https://lists.apache.org/thread.html/rfe62fbf9d4c314f166fe8c668e50e5d9dd882a99447f26f0367474bf%40%3Cusers.tomcat.apache.org%3E
- [other] https://lists.apache.org/thread.html/rf6d5d57b114678d8898005faef31e9fd6d7c981fcc4ccfc3bc272fc9%40%3Cdev.tomcat.apache.org%3E
- [other] https://lists.apache.org/thread.html/rfe62fbf9d4c314f166fe8c668e50e5d9dd882a99447f26f0367474bf%40%3Cannounce.tomcat.apache.org%3E
- [other] http://www.openwall.com/lists/oss-security/2021/03/01/2
- [other] https://lists.apache.org/thread.html/r8dd19c514face6dd85fd4eab0271854883f40c7307926c1f7cd5400c%40%3Ccommits.tomee.apache.org%3E
- [other] https://www.oracle.com/security-alerts/cpuApr2021.html
- [other] https://lists.apache.org/thread.html/r8a2ac0e476dbfc1e6440b09dcc782d444ad635d6da26f0284725a5dc%40%3Cusers.tomcat.apache.org%3E
- [other] https://lists.apache.org/thread.html/rb51ccd58b2152fc75125b2406fc93e04ca9d34e737263faa6ff0f41f%40%3Cusers.tomcat.apache.org%3E
- [other] https://lists.apache.org/thread.html/r11ce01e8a4c7269b88f88212f21830edf73558997ac7744f37769b77%40%3Cusers.tomcat.apache.org%3E
- [other] https://lists.apache.org/thread.html/rc1778b38e74b5b6142414d57623bd55b023a72361f422836782fca3c%40%3Cdev.tomcat.apache.org%3E
- [other] https://www.oracle.com//security-alerts/cpujul2021.html
- [other] https://www.oracle.com/security-alerts/cpuoct2021.html
- [other] https://www.oracle.com/security-alerts/cpujan2022.html
- [other] https://www.oracle.com/security-alerts/cpujul2022.html

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.