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CVE Record

CVE-2020-1938: When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache...

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. 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.

CriticalCVSS 9.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

This issue affects Apache Tomcat systems where the AJP connector is reachable by untrusted users. AJP was treated as more trusted than HTTP, and vulnerable defaults exposed it broadly. Attackers with network access to AJP could read application files and, in specific upload/control scenarios, potentially execute code.

Executive priority

Treat as urgent where vulnerable Tomcat has reachable AJP. The business risk is unauthorized file access and possible server compromise. Prioritize externally reachable systems first, then shared internal networks, development environments, and packaged applications embedding Tomcat.

Technical view

CVE-2020-1938 is an AJP request injection and potential remote code execution flaw in Apache Tomcat 9.0.0.M1-9.0.0.30, 8.5.0-8.5.50, and 7.0.0-7.0.99. Exposure depends on whether the AJP port is accessible to untrusted users. Apache states fixed versions include 9.0.31, 8.5.51, and 7.0.100 or later.

Likely exposure

Highest exposure is vulnerable Tomcat with AJP enabled and reachable from the internet, partner networks, shared hosting, or broad internal networks. Systems with AJP disabled or restricted to trusted front-end servers are materially less exposed, based on the supplied Apache guidance.

Exploitation context

The supplied sources do not show CISA KEV listing or confirmed active exploitation. The described impact is severe because reachable AJP can expose web application files and may enable code execution if an attacker can place or control content processed as JSP.

Researcher notes

The key exposure condition is network reachability of AJP, not merely running Tomcat. RCE requires an additional condition: attacker-controlled content inside the web application or another way to control web application content. Evidence in the bundle supports upgrade and AJP hardening, but not active exploitation claims.

Mitigation direction

  • Upgrade Tomcat to 9.0.31, 8.5.51, 7.0.100, or later.
  • Disable the AJP connector if it is not required.
  • Restrict AJP access to trusted front-end servers only.
  • Review Tomcat AJP configuration after upgrading, because defaults changed.
  • Check vendor or distribution guidance for packaged Tomcat builds.

Validation and detection

  • Inventory Apache Tomcat versions across production and internal environments.
  • Confirm whether AJP is enabled on each Tomcat instance.
  • Verify AJP is not reachable from untrusted networks.
  • Review applications for upload paths stored inside the web application.
  • Confirm upgraded instances still have intended front-end proxy behavior.
Prepared
Confidence
high
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2020-1938 mapping review

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
39Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.8CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

9.8Critical
CVSS 3.1 vector shape for CVE-2020-1938Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
ApacheApache TomcatApache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50, 7.0.0 to 7.0.99Listed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.