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Highest advisory severityHigh 3 vendors · 3 advisories

CVE-2026-66299

Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example

CVE-2026-66299: Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example. Not in the CISA KEV catalog.

Compare the source-linked records below. Ratings and product/version details belong to each advisory; they are not a single CVE-wide score or proof that every listed product is affected. How VulniPulse collects and checks evidence.

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CVE-2026-66299 key facts

CISA KEV
Not listed (catalog checked )
Highest advisory severity
High
CVSS base score
7.5 (Apache), 7.5 (NetApp), 5.3 (Red Hat)
CVSS vector
  • CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L (Red Hat)
Weakness
CWE-770
Fixed releases
  • Apache: 11.0.25, 10.1.58, 9.0.121
  • Red Hat: 11.0.25, 10.1.58, 9.0.121, jws6-tomcat-0:10.1.49-16.redhat_00016.1.el10jws, jws6-tomcat-0:10.1.49-16.redhat_00016.1.el8jws, jws6-tomcat-0:10.1.49-16.redhat_00016.1.el9jws and 4 more in the advisory
Vendor advisories
3 from Apache, NetApp, Red Hat
VulniPulse record
Published · Updated

Scores, vectors, weaknesses and fixed releases are quoted from vendor advisories that cover only CVE-2026-66299; bulletin-wide values are not repeated here.

Is CVE-2026-66299 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-66299 is not in the CISA KEV catalog (checked ) and no tracked advisory for it reports exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-66299?

Upgrade to a fixed release named by the vendor:

  • Apache: 11.0.25, 10.1.58, 9.0.121
  • Red Hat: 11.0.25, 10.1.58, 9.0.121, jws6-tomcat-0:10.1.49-16.redhat_00016.1.el10jws, jws6-tomcat-0:10.1.49-16.redhat_00016.1.el8jws, jws6-tomcat-0:10.1.49-16.redhat_00016.1.el9jws
  • Users who have followed the security guidance to remove the examples web application are not affected by this issue. (Apache)
  • Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), which fix the issue. (Apache)
  • To mitigate this vulnerability, remove the `examples` web application from your Apache Tomcat installation. This can typically be achieved by deleting the `examples` directory or `examples.war` file from the `webapps` directory of your Tomcat installation. A restart of the Tomcat service may be required for the changes to take full effect. (Red Hat)

Vendor advisory comparison

Apache

1 advisory
  • Advisory severityHigh7.5

    High [CVE-2026-66299] Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example

    CVE-2026-66299Source published Source updated

    Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example. This issue affects Apache Tomcat: from 11.0.0-M20 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web application are not affected by this issue. Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), which fix the issue.

    Affected products in this advisory
    • Apache Tomcat
    Source-reported affected versions
    • 11.0.0-M20 through 11.0.24
    • 10.1.24 through 10.1.57
    • 9.0.89 through 9.0.120.
    • through 9.0.120
    Source-reported fixed versions
    • 11.0.25
    • 10.1.58
    • 9.0.121
    Mitigation guidance
    • Users who have followed the security guidance to remove the examples web application are not affected by this issue.
    • Users are recommended to remove the examples web application or to upgrade to version 11.0.25, 10.1.58 or 9.0.121 (when released), which fix the issue.
    Full advisory and evidenceOpen source bulletin

NetApp

1 advisory
  • Advisory severityHigh7.5

    High [CVE-2026-66299] Apache Tomcat Vulnerability in NetApp Products

    NTAP-20260902-0018Source published Source updated

    Apache Tomcat versions 11.0.0-M20 through 11.0.24, 10.1.24 through 10.1.57, and 9.0.89 through 9.0.120 are susceptible to a vulnerability which when successfully exploited could lead to Denial of Service (DoS). Successful exploitation of this vulnerability could lead to Denial of Service (DoS). NetApp reports that one or more additional products remain under investigation; review the canonical advisory for current status. NetApp states there is no workaround available at this time.

    Affected products in this advisory
    No product details extracted. Check the source bulletin.
    Source-reported affected versions
    • 11.0.0
    • 11.0.24
    • 10.1.24
    • 10.1.57

    2 more entries in the full advisory.

    Source-reported fixed versions
    No fixed-version detail extracted. This does not mean no fix exists.
    Mitigation guidance
    No mitigation guidance extracted; consult the source.
    Full advisory and evidenceOpen source bulletin

Red Hat

1 advisory
  • Advisory severityMedium5.3

    Medium [CVE-2026-66299] Denial of Service via WebSocket chat example

    CVE-2026-66299Source published Source updated

    Uncontrolled Resource Consumption vulnerability in Apache Tomcat's WebSocket chat example. This issue affects Apache Tomcat: from 11.0.0-M20 through 11.0.24, from 10.1.24 through 10.1.57, from 9.0.89 through 9.0.120. Users who have followed the security guidance to remove the examples web application are not affected by this issue. This can lead to the affected system becoming unresponsive or crashing. The impact is limited as the vulnerable component is part of an example application, which is generally not deployed in production environments. Exploitation requires the example application to be present and accessible. Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L). Weakness: CWE-770. Affected Red Hat products: Red Hat JBoss Web Server 6.2.5; Red Hat…

    Affected products in this advisory
    • Red Hat JBoss Web Server 6.2.5
    • Red Hat JBoss Web Server 6.2 on RHEL 10
    • Red Hat JBoss Web Server 6.2 on RHEL 8
    • Red Hat JBoss Web Server 6.2 on RHEL 9

    5 more entries in the full advisory.

    Source-reported affected versions
    • 11.0.0
    • 11.0.24
    • 10.1.24
    • 10.1.57

    2 more entries in the full advisory.

    Source-reported fixed versions
    • 11.0.25
    • 10.1.58
    • 9.0.121
    • jws6-tomcat-0:10.1.49-16.redhat_00016.1.el10jws

    6 more entries in the full advisory.

    Mitigation guidance
    • To mitigate this vulnerability, remove the `examples` web application from your Apache Tomcat installation. This can typically be achieved by deleting the `examples` directory or `examples.war` file from the `webapps` directory of your Tomcat installation. A restart of the Tomcat service may be required for the changes to take full effect.
    Full advisory and evidenceOpen source bulletin

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