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NVD / CVE Program· CNA apache

CVE-2021-42340: DoS via memory leak with WebSocket connections

Noroxi assessment

Priority: Monitor (action score 34/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 11.7% (FIRST EPSS); higher than 96% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: tomcat9 (Debian:11) 9.0.43-2~deb11u3; tomcat9 (Debian:12) 9.0.54-1; org.apache.tomcat:tomcat (Maven) 10.0.12, 10.1.0-M6, 8.5.72.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to tomcat9 (Debian:11) 9.0.43-2~deb11u3; tomcat9 (Debian:12) 9.0.54-1; org.apache.tomcat:tomcat (Maven) 10.0.12, 10.1.0-M6, 8.5.72 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

The fix for bug 63362 present in Apache Tomcat 10.1.0-M1 to 10.1.0-M5, 10.0.0-M1 to 10.0.11, 9.0.40 to 9.0.53 and 8.5.60 to 8.5.71 introduced a memory leak. The object introduced to collect metrics for HTTP upgrade connections was not released for WebSocket connections once the connection was closed. This created a memory leak that, over time, could lead to a denial of service via an OutOfMemoryError.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Oct 14, 2021
Updated
Jun 17, 2026
EPSS
11.7% · 96th percentile

Report tools

JSON

Action score

34

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
4 / 30 · 11.7%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
apachetomcat
netapphci
netappmanagement services for element software
debiandebian linux
oracleagile engineering data management
oraclebig data spatial and graph
oraclecommunications diameter signaling router
oraclehospitality cruise shipboard property management system
oraclemanaged file transfer
oraclemiddleware common libraries and tools
oraclepayment interface
oracleretail customer insights

and 6 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • apache tomcat8.5.60 and later · before 8.5.72
  • apache tomcat9.0.40 and later · before 9.0.54
  • apache tomcat10.0.1 and later · before 10.0.12
  • apache tomcat10.0.0
  • apache tomcat10.1.0
  • debian debian linux11.0
  • netapp hciall versions
  • netapp management services for element softwareall versions
  • oracle agile engineering data management6.2.1.0
  • oracle big data spatial and graphbefore 23.1
  • oracle communications diameter signaling router8.0.0.0 and later · up to 8.5.0.2 inclusive
  • oracle hospitality cruise shipboard property management system20.1.0
  • oracle managed file transfer12.2.1.3.0
  • oracle managed file transfer12.2.1.4.0
  • oracle middleware common libraries and tools12.2.1.4.0
  • oracle payment interface19.1
  • oracle payment interface20.3
  • oracle retail customer insights15.0.2
  • oracle retail customer insights16.0.2
  • oracle retail data extractor for merchandising15.0.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (apache). Independent of NVD's CPE analysis and usually ahead of it.

  • Apache Software Foundation Apache Tomcat

    • Apache Tomcat 10 10.0.0-M10 to 10.0.11, Apache Tomcat 10 10.1.0-M1 to 10.1.0-M5, Apache Tomcat 9 9.0.40 to 9.0.53, Apache Tomcat 8 8.5.60 to 8.5.71affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:11tomcat9before 9.0.43-2~deb11u39.0.43-2~deb11u3
Debian:12tomcat9before 9.0.54-19.0.54-1
Mavenorg.apache.tomcat:tomcatfrom 10.0.0-M1 · before 10.0.1210.0.12
Mavenorg.apache.tomcat:tomcatfrom 10.1.0-M1 · before 10.1.0-M610.1.0-M6
Mavenorg.apache.tomcat:tomcatfrom 8.5.60 · before 8.5.728.5.72
Mavenorg.apache.tomcat:tomcatfrom 9.0.40 · before 9.0.549.0.54
Red Hat:enterprise_linux:9::appstreampki-servlet-4.0-apibefore 1:9.0.50-1.el91:9.0.50-1.el9
Red Hat:enterprise_linux:9::appstreampki-servlet-enginebefore 1:9.0.50-1.el91:9.0.50-1.el9
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcatbefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-admin-webappsbefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-docs-webappbefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-el-3.0-apibefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-java-jdk11before 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-java-jdk8before 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-javadocbefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-jsp-2.3-apibefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-libbefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-nativebefore 0:1.2.30-3.redhat_3.el7jws0:1.2.30-3.redhat_3.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-native-debuginfobefore 0:1.2.30-3.redhat_3.el7jws0:1.2.30-3.redhat_3.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-selinuxbefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-servlet-4.0-apibefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-vaultbefore 0:1.1.8-4.Final_redhat_00004.1.el7jws0:1.1.8-4.Final_redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-vault-javadocbefore 0:1.1.8-4.Final_redhat_00004.1.el7jws0:1.1.8-4.Final_redhat_00004.1.el7jws
Red Hat:jboss_enterprise_web_server:5.6::el7jws5-tomcat-webappsbefore 0:9.0.50-3.redhat_00004.1.el7jws0:9.0.50-3.redhat_00004.1.el7jws

+14

Same product

apache: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-24813Apache Tomcat: Potential RCE and/or information disclosure and/or information corruption with partial PUTKEV
    99Now
  • CVE-2016-8735Remote code execution is possible with Apache Tomcat before 6.0.48, 7.x before 7.0.73, 8.x before 8.0.39, 8.5.x before 8.5.7, and 9.x beforeKEV
    96Now
  • CVE-2017-12617When running Apache Tomcat versions 9.0.0.M1 to 9.0.0, 8.5.0 to 8.5.22, 8.0.0.RC1 to 8.0.46 and 7.0.0 to 7.0.81 with HTTP PUTs enabled (e.g.KEV
    92Now

Published before and after this one in the same product

  • ← EarlierCVE-2021-33037Jul 12, 2021 · Incorrect Transfer-Encoding handling with HTTP/1.0
    43Plan
  • ← EarlierCVE-2021-41079Sep 16, 2021 · Apache Tomcat DoS with unexpected TLS packet
    32Monitor
  • Later →CVE-2022-23181Jan 27, 2022 · Local privilege escalation with FileStore
    28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:tomcat99.0.54-1 · Debian:12Package registry (OSV)
Maven:org.apache.tomcat:tomcat10.0.12Package registry (OSV)
Maven:org.apache.tomcat:tomcat10.1.0-M6Package registry (OSV)
Maven:org.apache.tomcat:tomcat8.5.72Package registry (OSV)
Maven:org.apache.tomcat:tomcat9.0.54Package registry (OSV)
red hat:jws5-tomcat0:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-admin-webapps0:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-docs-webapp0:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-el-3.0-api0:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-java-jdk110:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-java-jdk80:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-javadoc0:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-jsp-2.3-api0:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-lib0:9.0.50-3.redhat_00004.1.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:jws5-tomcat-native0:1.2.30-3.redhat_3.el7jws · Red Hat:jboss_enterprise_web_server:5.6::el7Package registry (OSV)
red hat:pki-servlet-4.0-api1:9.0.50-1.el9 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:pki-servlet-engine1:9.0.50-1.el9 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-772 · Missing Release of Resource after Effective Lifetime

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (8 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records