CVE-2020-9484

HIGHNVD 7.09.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because EPSS predicts 93% probability of exploitation within the next 30 days (top 0.2% of all CVEs). NVD baseline CVSS 7.0 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, nvd
Elevated
7.0
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • 186 internet-exposed hosts are running an affected version right now
  • High exploitation likelihood — EPSS 57%
CISA-KEV: Not listedEPSS: 57%CVSS: 7.0Exploit: NoneExposed: 186

A fix is available — apply it.

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.

Live · internet exposure

186 internet-exposed hosts are running an affected version of CVE-2020-9484 right now.

across 35 countries (United States, Germany, China, Japan, Korea, Republic of)top: tomcat
See the live KEV-Exposure radar →Found passively from public internet-scan data — aggregate, host-redacted.

EchelonGraph is the only CVE feed that fuses live vulnerability intelligence with its own live internet-exposure radar — so you see not just that a CVE is exploited, but how much of the internet is exposed to it right now.

CVSS v3
7.0
EG Score
9.0(high)
EPSS
99.0%
KEV
Not listed

Published

May 20, 2020

Last Modified

November 21, 2024

References (84)

Vendor Advisories for CVE-2020-9484(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(6)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatpatch2022-07-07redhat
redhattomcat2021-08-11redhat
redhattomcat6-0:6.0.24-115.el6_102020-06-11redhat
redhattomcat-0:7.0.76-12.el7_82020-06-11redhat
redhattomcat-native-0:1.2.23-22.redhat_22.ep7.el72020-06-10redhat
redhatjws5-tomcat-native-0:1.2.23-5.redhat_5.el8jws2020-06-10redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(2 across 1 ecosystem)
Maven(2)
PackageVulnerable rangeFixed inDependents
org.apache.tomcat.embed:tomcat-embed-core7.0.0 ... 7.0.99 (70 versions)7.0.104—
org.apache.tomcat:tomcat-catalina7.0.0 ... 7.0.99 (70 versions)7.0.104—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(8)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 7× in last 7d / 33× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:05 UTCEPSS rescore
  2. 2026-07-20 17:04 UTCEPSS rescore
  3. 2026-07-20 17:04 UTCEPSS rescore
  4. 2026-07-19 12:00 UTCOSV refresh
  5. 2026-07-19 02:26 UTCEPSS rescore
  6. 2026-07-19 02:26 UTCEPSS rescore
  7. 2026-07-16 17:00 UTCEPSS rescore
  8. 2026-07-15 16:55 UTCEPSS rescore
  9. 2026-07-15 16:55 UTCEPSS rescore
  10. 2026-07-13 22:27 UTCEPSS rescore
  11. 2026-07-13 22:27 UTCEPSS rescore
  12. 2026-07-13 06:10 UTCEPSS rescore
  13. 2026-07-13 06:10 UTCEPSS rescore
  14. 2026-07-12 05:44 UTCEPSS rescore
  15. 2026-07-12 05:44 UTCEPSS rescore
  16. 2026-07-09 19:07 UTCEPSS rescore
  17. 2026-07-07 13:43 UTCEPSS rescore
  18. 2026-07-06 16:25 UTCEPSS rescore
  19. 2026-07-05 02:28 UTCEPSS rescore
  20. 2026-07-05 02:28 UTCEPSS rescore
  21. 2026-07-02 16:57 UTCEPSS rescore
  22. 2026-07-01 21:01 UTCOSV refresh
  23. 2026-07-01 15:03 UTCEPSS rescore
  24. 2026-06-30 23:20 UTCEPSS rescore
  25. 2026-06-30 23:20 UTCEPSS rescore
Show 29 more
  1. 2026-06-28 04:54 UTCEPSS rescore
  2. 2026-06-28 04:54 UTCEPSS rescore
  3. 2026-06-27 03:06 UTCEPSS rescore
  4. 2026-06-27 03:06 UTCEPSS rescore
  5. 2026-06-25 13:48 UTCEPSS rescore
  6. 2026-06-25 13:48 UTCEPSS rescore
  7. 2026-06-23 21:31 UTCEPSS rescore
  8. 2026-06-23 21:31 UTCEPSS rescore
  9. 2026-06-21 01:57 UTCEPSS rescore
  10. 2026-06-21 01:57 UTCEPSS rescore
  11. 2026-06-18 17:51 UTCEPSS rescore
  12. 2026-06-18 17:50 UTCEPSS rescore
  13. 2026-06-17 17:50 UTCEPSS rescore
  14. 2026-06-16 17:50 UTCEPSS rescore
  15. 2026-06-15 17:46 UTCEPSS rescore
  16. 2026-06-14 02:43 UTCOSV refresh
  17. 2026-06-12 23:10 UTCEPSS rescore
  18. 2026-06-12 23:10 UTCEPSS rescore
  19. 2026-06-11 13:58 UTCEPSS rescore
  20. 2026-06-11 13:58 UTCEPSS rescore
  21. 2026-06-10 22:16 UTCEPSS rescore
  22. 2026-06-05 06:08 UTCEPSS rescore
  23. 2026-06-05 06:08 UTCEPSS rescore
  24. 2026-05-31 00:15 UTCEPSS rescore
  25. 2026-05-31 00:15 UTCEPSS rescore
  26. 2026-05-27 03:27 UTCEG score recompute
  27. 2026-05-27 03:27 UTCVendor advisory
  28. 2026-05-26 13:42 UTCEPSS rescore
  29. 2026-05-26 13:42 UTCEPSS rescore

Publicly available exploits

(10 references)

Working exploit code is in the public domain (10 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoC0dayCTF/CVE-2020-9484
    First seen Sep 16, 2024

    Remake of CVE-2020-9484 by Pentestical

    Open source ↗
  • GitHub PoCd3fudd/CVE-2020-9484_Exploit
    First seen Nov 14, 2022

    Exploit for Apache Tomcat deserialization (CVE-2020-9484) which could lead to RCE

    Open source ↗
  • GitHub PoCRepublicR0K/CVE-2020-9484
    First seen May 18, 2021

    Apache Tomcat RCE (CVE-2020-9484)

    Open source ↗
  • GitHub PoCVICXOR/CVE-2020-9484
    First seen Feb 10, 2021

    POC for CVE-2020-9484

    Open source ↗
  • GitHub PoCPenTestical/CVE-2020-9484
    First seen Dec 31, 2020
    Open source ↗
  • GitHub PoCanjai94/CVE-2020-9484-exploit
    First seen Sep 5, 2020
    Open source ↗
  • GitHub PoCosamahamad/CVE-2020-9484-Mass-Scan
    First seen Jun 5, 2020

    CVE-2020-9484 Mass Scanner, Scan a list of urls for Apache Tomcat deserialization (CVE-2020-9484) which could lead to RCE

    Open source ↗
  • GitHub PoCIdealDreamLast/CVE-2020-9484
    First seen May 21, 2020

    用Kali 2.0复现Apache Tomcat Session反序列化代码执行漏洞

    Open source ↗
  • GitHub PoCmasahiro331/CVE-2020-9484
    First seen May 21, 2020
    Open source ↗
  • GitHub PoCthreedr3am/tomcat-cluster-session-sync-exp
    First seen May 19, 2020

    tomcat使用了自带session同步功能时，不安全的配置（没有使用EncryptInterceptor）导致存在的反序列化漏洞，通过精心构造的数据包， 可以对使用了tomcat自带session同步功能的服务器进行攻击。PS:这个不是CVE-2020-9484，9484是session持久化的洞，这个是session集群同步的洞！

    Open source ↗

Frequently asked(5)

What is CVE-2020-9484?
CVE-2020-9484 is a high vulnerability published on May 20, 2020. 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…
When was CVE-2020-9484 disclosed?
CVE-2020-9484 was first published in the National Vulnerability Database on May 20, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-9484 actively exploited?
CVE-2020-9484 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-9484?
CVE-2020-9484 has a CVSS v3 base score of 7.0 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2020-9484?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-9484, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-9484

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