CVE-2020-1938 · Ghostcat
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When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat
rank 81 = 40 + 25 + 0 + 10 + 6
rank@v1 · act now
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.99270 · CISA KEV listed · without this subject the record ranks 41
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 9.8, from NVD · without this subject the record ranks 56
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
no persisting rise in 365 days · without this subject the record ranks 81
How much of the world it touches
NVD CPE configurations
20 products in the CPE ranges · without this subject the record ranks 71
Someone else already set the date
CISA KEV remediation due date
CISA remediation date held · without this subject the record ranks 75
$4.95M = $4.99M incident cost x 1 exposure x 0.9927 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
Hindsight · the state
Foresight · where to check next
No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.
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The fix, and how long it's been waiting.
Exploit Status & Known PoCs a ladder, not a score
Current rung: Exploited in the wild · CISA KEV listed, 2022-03-03.
Affected & Fixed Versions as published
Show all 20 published ranges
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What it is stated by the CNA
Ghostcat is the common name for CVE-2020-1938. When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat. Tomcat treats AJP connections as having higher trust than, for example, a similar HTTP connection. If such connections are available to an attacker, they can be exploited in ways that may be surprising. In Apache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99, Tomcat shipped with an AJP Connector enabled by default that listened on all configured IP addresses. It was expected (and recommended in the security guide) that this Connector would be disabled if not required. cve-aliases@2026-08-27
Read the rest of the CNA's description
This vulnerability report identified a mechanism that allowed: - returning arbitrary files from anywhere in the web application - processing any file in the web application as a JSP Further, if the web application allowed file upload and stored those files within the web application (or the attacker was able to control the content of the web application by some other means) then this, along with the ability to process a file as a JSP, made remote code execution possible. It is important to note that mitigation is only required if an AJP port is accessible to untrusted users. Users wishing to take a defence-in-depth approach and block the vector that permits returning arbitrary files and execution as JSP may upgrade to Apache Tomcat 9.0.31, 8.5.51 or 7.0.100 or later. A number of changes were made to the default AJP Connector configuration in 9.0.31 to harden the default configuration. It is likely that users upgrading to 9.0.31, 8.5.51 or 7.0.100 or later will need to make small changes to their configurations.
NVD's analysis a second authority
- severity
- 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- affected versions
- apache geode 1.12.0; apache tomcat >= 7.0.0 < 7.0.100; apache tomcat >= 8.5.0 < 8.5.51; and 17 more, listed in full below
- also scored by
- 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
check it yourself lists.apache.org lists.apache.org lists.apache.org lists.apache.org lists.apache.org lists.apache.org +14 morereceipt
Dated events
Movement the material steps
Show all 30 observations
30 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
Listed by CISA 738 days after it published and the record had been public for 6 years, 6 months when this index was last written.
No material movement in 81 days as of the last ingest this index recorded.
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What usually comes next
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