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Weblogic ServerApplication · Oracle

CVE-2021-35620

HIGH · 7.5 CVSS v3.1 Published 2021-10-20
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Vulnerability in the Oracle WebLogic Server product of Oracle Fusion Middleware (component: Core). Supported versions that are affected are 10.3.6.0.0, 12.1.3.0.0, 12.2.1.3.0, 12.2.1.4.0 and 14.1.1.0.0. Easily exploitable vulnerability allows unauthenticated attacker with network access via T3 to compromise Oracle WebLogic Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Oracle WebLogic Server. CVSS 3.1 Base Score 7.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

CVE-2021-35620 is a denial-of-service vulnerability in Oracle WebLogic Server's Core component. An unauthenticated remote attacker with network access via the T3 protocol can send specially crafted requests that cause the WebLogic Server to hang or crash repeatedly, resulting in complete service unavailability.

MitigationApply the Oracle Critical Patch Update (CPU) for October 2021 or later. As a compensating control, restrict network access to T3 ports (typically 7001) via firewall or disable T3 protocol if not required for the application.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Weblogic ServerApplication
Affected:= 10.3.6.0.0= 12.1.3.0.0= 12.2.1.3.0= 12.2.1.4.0= 14.1.1.0.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify WebLogic Server installation
    Locate the WebLogic installation directory. On Unix systems, common paths are /oracle/weblogic, /u01/oracle/weblogic, or under the Oracle Middleware home. On Windows, check C:\Oracle\WebLogic or similar. Look for the directory containing the 'wlserver' folder.
    Affected if WebLogic Server is not found on the system.
  2. Determine installed WebLogic version
    Check the version file in the WebLogic installation. Common locations: <WL_HOME>/welcomepages/VERSION.txt, <WL_HOME>/registry.xml, or the 'About WebLogic Server' entry in the administration console. Run: java -jar <WL_HOME>/server/lib/weblogic.jar -verbose to display version information.
    Affected if The installed version matches 10.3.6.0.0, 12.1.3.0.0, 12.2.1.3.0, 12.2.1.4.0, or 14.1.1.0.0.
  3. Verify T3 protocol is enabled
    T3 protocol is typically enabled by default on WebLogic. Check the administration console under Server > [server_name] > Protocols > Enable T3, or inspect the config.xml file in the domain config directory for <server> entries with <protocol>t3</protocol>. Also check for Enable T3 on the Server Configuration page.
    Affected if T3 protocol is enabled or the setting is not explicitly disabled.
  4. Check T3 port network exposure
    Identify the configured T3 port (default 7001) from the Server configuration. Run 'netstat -an | grep 7001' or 'ss -tlnp | grep 7001' to see if the port is listening. Verify if the listener is bound to 0.0.0.0 (all interfaces) or an external IP address.
    Affected if The T3 port (commonly 7001) is listening on a network-accessible interface.

You are affected if you have WebLogic Server version 10.3.6.0.0, 12.1.3.0.0, 12.2.1.3.0, 12.2.1.4.0, or 14.1.1.0.0 running with T3 protocol enabled and the T3 port exposed to network access.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Oracle Critical Patch Update (CPU) for October 2021 or later. As a compensating control, restrict network access to T3 ports (typically 7001) via firewall or disable T3 protocol if not required for the application.

Fix this in Weblogic Server Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,580
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-35620 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data