CVE-2020-13934: Apache Tomcat Improper Restriction Of Operations Within Vulnerability

HIGH
Advisory Identifier: GHSA-vf77-8h7g-gghp
Share
CVSS 7.5
CWE-476 CWE-119
Published
Advisory Summary

CVE-2020-13934 is a HIGH (CVSS 7.5) improper restriction of operations within vulnerability (CWE-476: NULL Pointer Dereference) affecting Apache Tomcat libraries in the Maven ecosystem. The issue involves improper restriction of operations within the bounds of a memory buffer in apache tomcat. Remediation is available by upgrading affected packages to version 10.0.0-M6, 9.0.36, 8.5.56.

CVE-2020-13934 at a Glance

CVE Identifier CVE-2020-13934
GHSA Identifier GHSA-vf77-8h7g-gghp
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-476: NULL Pointer Dereference
Affected Product Apache Tomcat
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2020-13934

To remediate this vulnerability, upgrade all affected Apache Tomcat dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.apache.tomcat:tomcat fixed: 10.0.0-M6 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>10.0.0-M6</version>
</dependency>
org.apache.tomcat:tomcat fixed: 9.0.36 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>9.0.36</version>
</dependency>
org.apache.tomcat:tomcat fixed: 8.5.56 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>8.5.56</version>
</dependency>
org.apache.tomcat:tomcat-coyote fixed: 10.0.0-M6 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-coyote</artifactId>
    <version>10.0.0-M6</version>
</dependency>
org.apache.tomcat:tomcat-coyote fixed: 9.0.36 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-coyote</artifactId>
    <version>9.0.36</version>
</dependency>
org.apache.tomcat:tomcat-coyote fixed: 8.5.56 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-coyote</artifactId>
    <version>8.5.56</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.apache.tomcat

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2020-13934, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.apache.tomcat

Analyze the terminal output to locate any version of Apache Tomcat in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 10.0.0-M6), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.apache.tomcat command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-476: NULL Pointer Dereference, where the product dereferences a pointer that it expects to be valid but is null. In Apache Tomcat, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

An h2c direct connection to Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M5 to 9.0.36 and 8.5.1 to 8.5.56 did not release the HTTP/1.1 processor after the upgrade to HTTP/2. If a sufficient number of such requests were made, an OutOfMemoryException could occur leading to a denial of service.

CVE-2020-13934 Affected Apache Tomcat Versions

6 component(s)
Fixed Versions:
10.0.0-M69.0.368.5.56
Product / Package Ecosystem Affected Versions Fixed Version
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
≥ 10.0.0-M1
< 10.0.0-M6
10.0.0-M6
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
≥ 9.0.0.M5
< 9.0.36
9.0.36
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
≥ 8.5.1
< 8.5.56
8.5.56
org.apache.tomcat:tomcat-coyote
maven/org.apache.tomcat/tomcat-coyote
Maven
≥ 10.0.0-M1
< 10.0.0-M6
10.0.0-M6
org.apache.tomcat:tomcat-coyote
maven/org.apache.tomcat/tomcat-coyote
Maven
≥ 9.0.0.M5
< 9.0.36
9.0.36
org.apache.tomcat:tomcat-coyote
maven/org.apache.tomcat/tomcat-coyote
Maven
≥ 8.5.1
< 8.5.56
8.5.56

References

usn.ubuntu.com/4596-1 WEB
https://usn.ubuntu.com/4596-1
NVD — CVE-2020-13934 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-13934
Apache Tomcat Source Repository REPOSITORY
https://github.com/apache/tomcat
lists.apache.org/thread.html/r61f411... WEB
https://lists.apache.org/thread.html/r61f411cf82488d6ec213063fc15feeeb88e31b0ca9c29652ee4f962e%40%3Cannounce.tomcat.apache.org%3E
lists.apache.org/thread.html/ra072b1... WEB
https://lists.apache.org/thread.html/ra072b1f786e7d139e86f1d1145572e0ff71cef38a96d9c6f5362aac8@%3Cdev.tomcat.apache.org%3E
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2020/07/msg00017.html
Apache Tomcat Security Information SECURITY
https://security.netapp.com/advisory/ntap-20200724-0003
Apache Tomcat Security Information SECURITY
https://www.debian.org/security/2020/dsa-4727
Apache Tomcat Security Information SECURITY
https://www.oracle.com//security-alerts/cpujul2021.html
Apache Tomcat Security Information SECURITY
https://www.oracle.com/security-alerts/cpuApr2021.html
Apache Tomcat Security Information SECURITY
https://www.oracle.com/security-alerts/cpujan2021.html
Apache Tomcat Security Information SECURITY
https://www.oracle.com/security-alerts/cpujan2022.html
Apache Tomcat Security Information SECURITY
https://www.oracle.com/security-alerts/cpuoct2020.html
Apache Tomcat Security Information SECURITY
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00084.html
Apache Tomcat Security Information SECURITY
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00088.html

Frequently Asked Questions

What is CVE-2020-13934?
CVE-2020-13934 is a security vulnerability in Apache Tomcat involving Improper Restriction of Operations within the Bounds of a Memory Buffer in Apache Tomcat under CWE-476: NULL Pointer Dereference.
Which Apache Tomcat versions are affected?
Affected versions include releases prior to 10.0.0-M6, 9.0.36, 8.5.56 across affected packages: org.apache.tomcat:tomcat, org.apache.tomcat:tomcat-coyote.
What version fixes CVE-2020-13934?
Upgrading to 10.0.0-M6, 9.0.36, 8.5.56 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tomcat affected?
Yes, org.apache.tomcat:tomcat is affected in releases prior to 10.0.0-M6, 9.0.36, 8.5.56. Upgrade your dependency to 10.0.0-M6, 9.0.36, 8.5.56 or later.
Is tomcat-coyote affected?
Yes, org.apache.tomcat:tomcat-coyote is affected in releases prior to 10.0.0-M6, 9.0.36, 8.5.56. Upgrade your dependency to 10.0.0-M6, 9.0.36, 8.5.56 or later.
What is the CVSS score of CVE-2020-13934?
CVE-2020-13934 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2020-13934?
CVE-2020-13934 is classified under CWE-476: NULL Pointer Dereference (The product dereferences a pointer that it expects to be valid but is NULL.).
How can I check Maven dependencies for CVE-2020-13934?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.apache.tomcat'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vf77-8h7g-gghp",
  "modified" : "2026-05-20T18:50:54Z",
  "published" : "2022-02-08T22:05:00Z",
  "aliases" : [ "CVE-2020-13934" ],
  "summary" : "Improper Restriction of Operations within the Bounds of a Memory Buffer in Apache Tomcat",
  "details" : "An h2c direct connection to Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M5 to 9.0.36 and 8.5.1 to 8.5.56 did not release the HTTP/1.1 processor after the upgrade to HTTP/2. If a sufficient number of such requests were made, an OutOfMemoryException could occur leading to a denial of service.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
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      "name" : "org.apache.tomcat:tomcat"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.0.0-M1"
      }, {
        "fixed" : "10.0.0-M6"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 10.0.0-M5"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.apache.tomcat:tomcat"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
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      }, {
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      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.apache.tomcat:tomcat"
    },
    "ranges" : [ {
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      } ]
    } ]
  }, {
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    },
    "ranges" : [ {
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    } ],
    "database_specific" : {
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    },
    "ranges" : [ {
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      }, {
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      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.apache.tomcat:tomcat-coyote"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.5.1"
      }, {
        "fixed" : "8.5.56"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-13934"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/apache/tomcat"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/r61f411cf82488d6ec213063fc15feeeb88e31b0ca9c29652ee4f962e%40%3Cannounce.tomcat.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/ra072b1f786e7d139e86f1d1145572e0ff71cef38a96d9c6f5362aac8@%3Cdev.tomcat.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2020/07/msg00017.html"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20200724-0003"
  }, {
    "type" : "WEB",
    "url" : "https://usn.ubuntu.com/4596-1"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2020/dsa-4727"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com//security-alerts/cpujul2021.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpuApr2021.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpujan2021.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpujan2022.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpuoct2020.html"
  }, {
    "type" : "WEB",
    "url" : "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00084.html"
  }, {
    "type" : "WEB",
    "url" : "http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00088.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-119", "CWE-476" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-04-12T18:34:04Z",
    "nvd_published_at" : "2020-07-14T15:15:00Z"
  }
}