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Jboss RemotingApplication · Redhat

CVE-2020-35510

MEDIUM · 5.9 CVSS v3.1 Published 2021-06-02
Fix available
A fix is available. Upgrade to 5.0.20 or later.
See remediation →
68/100
Remediation priority · Elevated
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
A flaw was found in jboss-remoting in versions before 5.0.20.SP1-redhat-00001. A malicious attacker could cause threads to hold up forever in the EJB server by writing a sequence of bytes corresponding to the expected messages of a successful EJB client request, but omitting the ACK messages, or just tamper with jboss-remoting code, deleting the lines that send the ACK message from the EJB client code resulting in a denial of service. The highest threat from this vulnerability is to system availability.

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

A denial of service vulnerability exists in jboss-remoting versions before 5.0.20.SP1-redhat-00001 where malicious attackers can cause EJB server threads to hang indefinitely by sending client request messages without sending the required ACK messages, causing permanent thread blocking.

MitigationUpgrade jboss-remoting to version 5.0.20.SP1-redhat-00001 or later to patch the vulnerability.

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
Jboss RemotingApplication
Affected:< 5.0.20= 5.0.20

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/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. Locate jboss-remoting library
    Search for jboss-remoting jar files in the application and JBoss installation directories. Common paths include $JBOSS_HOME/lib, $JBOSS_HOME/modules, or the application's WEB-INF/lib folder. Identify the exact jar file name (typically jboss-remoting*.jar).
    Affected if jboss-remoting jar is present in the environment and version is 5.0.20 or below, or version is exactly 5.0.20 (not 5.0.20.SP1-redhat-00001 or later)
  2. Determine installed jboss-remoting version
    Extract version information from the jar file. Check the MANIFEST.MF file inside the jar for Specification-Version or Implementation-Version attributes, or use a command like 'jar tf jboss-remoting*.jar | grep MANIFEST' then 'unzip -p jboss-remoting*.jar META-INF/MANIFEST.MF'. Compare against affected version range.
    Affected if Version is less than 5.0.20.SP1-redhat-00001, or version equals exactly 5.0.20 (non-SP1)
  3. Verify EJB deployment
    Check if the server hosts Enterprise JavaBeans (EJB) applications. Look for EJB deployment descriptors (ejb-jar.xml) or annotations (@Stateless, @Stateful, @MessageDriven) in deployed applications. EJB is the attack surface for this vulnerability.
    Affected if EJB applications are deployed and the jboss-remoting service handles EJB client requests
  4. Assess remoting network exposure
    Identify network listeners configured for jboss-remoting. Check JBoss configuration files (standalone.xml, domain.xml) for <remoting> connectors or < acceptor> elements. Determine if the remoting port (typically 4447 or 8080) is accessible from untrusted networks.
    Affected if The EJB remoting interface is exposed to untrusted or public networks where malicious clients could connect and send requests without ACKs

Environment is affected if jboss-remoting version is below 5.0.20.SP1-redhat-00001 (or exactly 5.0.20) AND EJB over remoting is deployed AND the remoting port is accessible to untrusted clients.

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
Upgrade available Upgrade to 5.0.20 or later
Fixed in 5.0.20
Interim mitigation

Upgrade jboss-remoting to version 5.0.20.SP1-redhat-00001 or later to patch the vulnerability.

Fix this in Jboss Remoting Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
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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-2020-35510 in production — separate from our analysis above.

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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