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CVE Record

CVE-2021-30640: Auth weakness in JNDIRealm

A vulnerability in the JNDI Realm of Apache Tomcat allows an attacker to authenticate using variations of a valid user name and/or to bypass some of the protection provided by the LockOut Realm. This issue affects Apache Tomcat 10.0.0-M1 to 10.0.5; 9.0.0.M1 to 9.0.45; 8.5.0 to 8.5.65.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Apache Tomcat issue affects authentication when JNDIRealm is used. An attacker may authenticate with variations of a valid username or weaken LockOut Realm protections. Business impact depends on whether exposed Tomcat services use these realms for login control.

Executive priority

Treat as a targeted authentication-control risk. Prioritize externally reachable Tomcat applications and systems using directory-backed authentication. It is not KEV-listed in the provided evidence.

Technical view

CVE-2021-30640 is an authentication weakness in Apache Tomcat JNDIRealm. Reported affected ranges include Tomcat 10.0.0-M1 through 10.0.5, 9.0.0.M1 through 9.0.45, 8.5.0 through 8.5.65, and the bundle also lists 7.0.0 through 7.0.108.

Likely exposure

Exposure is most likely on Tomcat applications configured with JNDIRealm, especially where LockOut Realm is relied on for account lockout protection. Internet-facing login services raise urgency.

Exploitation context

The source bundle does not show CISA KEV listing or evidence of active exploitation. The issue is still security-relevant because it affects authentication behavior, not merely logging or disclosure.

Researcher notes

Evidence is limited to public advisories and CVE metadata. No CVSS, CWE, exploit detail, or confirmed exploitation is provided in the bundle. Validate exposure through realm configuration, not Tomcat presence alone.

Mitigation direction

  • Inventory Tomcat versions and identify affected ranges.
  • Check whether applications use JNDIRealm or LockOut Realm.
  • Upgrade Tomcat or vendor packages using Apache or distribution guidance.
  • Review Oracle, Debian, Gentoo, and appliance advisories where applicable.
  • Monitor authentication logs for username variation attempts.

Validation and detection

  • Confirm deployed Tomcat version against affected ranges.
  • Review server.xml and realm configuration for JNDIRealm usage.
  • Verify package versions from OS vendor security advisories.
  • Check authentication logs for lockout bypass indicators.
  • Document affected applications and remediation owner.
Prepared
Confidence
medium
Sources
7

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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CVE-2021-30640 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
0Timeline events
0ADP providers
10Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Apache Software FoundationApache TomcatApache Tomcat 10 10.0.0-M1 to 10.0.5, Apache Tomcat 9 9.0.0.M1 to 9.0.45, Apache Tomcat 8.5 8.5.0 to 8.5.65, Apache Tomcat 7 7.0.0 to 7.0.108Listed
Weakness

CWE details

No CWE listed

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