CVE-2021-33037: Apache Tomcat HTTP Request Smuggling Vulnerability

Q: What is CVE-2021-33037?

CVE-2021-33037 is a security vulnerability in Apache Tomcat involving HTTP Request Smuggling in Apache Tomcat under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling').

Q: Which Apache Tomcat versions are affected?

Affected versions include releases prior to 10.0.7, 9.0.48, 8.5.68 across affected packages: org.apache.tomcat:tomcat.

Q: What version fixes CVE-2021-33037?

Upgrading to 10.0.7, 9.0.48, 8.5.68 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is tomcat affected?

Yes, org.apache.tomcat:tomcat is affected in releases prior to 10.0.7, 9.0.48, 8.5.68. Upgrade your dependency to 10.0.7, 9.0.48, 8.5.68 or later.

Q: What is the CVSS score of CVE-2021-33037?

CVE-2021-33037 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

Q: What CWE is associated with CVE-2021-33037?

CVE-2021-33037 is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') (The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.).

Q: How can I check Maven dependencies for CVE-2021-33037?

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.

MODERATE

Advisory Identifier: GHSA-4vww-mc66-62m6

CVSS 5.3

CWE-444

Published 2021-08-13

Advisory Summary

CVE-2021-33037 is a MODERATE (CVSS 5.3) http request smuggling vulnerability (CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')) affecting Apache Tomcat libraries in the Maven ecosystem. The issue involves http request smuggling in apache tomcat. Remediation is available by upgrading affected packages to version 10.0.7, 9.0.48, 8.5.68.

CVE-2021-33037 at a Glance

CVE Identifier CVE-2021-33037

GHSA Identifier GHSA-4vww-mc66-62m6

Severity MODERATE

CVSS v3.1 Base Score 5.3

CWE Classification CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Affected Product Apache Tomcat

Package Ecosystem Maven

Published Date 2021-08-13

Last Updated 2024-03-11

Security Impact

CVSS: 5.3

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:L/A:N).

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 Low (I:L)

Availability None (A:N)

How to Fix CVE-2021-33037

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: 10.0.7

<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>10.0.7</version>
</dependency>

org.apache.tomcat:tomcat fixed: 9.0.48

<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>9.0.48</version>
</dependency>

org.apache.tomcat:tomcat fixed: 8.5.68

<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>8.5.68</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-2021-33037, 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 10.0.7), 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-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling'), where the product acts as an intermediary http agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed http requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. 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

Apache Tomcat 10.0.0-M1 to 10.0.6, 9.0.0.M1 to 9.0.46 and 8.5.0 to 8.5.66 did not correctly parse the HTTP transfer-encoding request header in some circumstances leading to the possibility to request smuggling when used with a reverse proxy. Specifically: - Tomcat incorrectly ignored the transfer encoding header if the client declared it would only accept an HTTP/1.0 response; - Tomcat honoured the identify encoding; and - Tomcat did not ensure that, if present, the chunked encoding was the final encoding.

CVE-2021-33037 Affected Apache Tomcat Versions

3 component(s)

Fixed Versions:

10.0.79.0.488.5.68

Product / Package	Ecosystem	Affected Versions	Fixed Version
org.apache.tomcat:tomcat maven/org.apache.tomcat/tomcat	Maven	≥ 10.0.0-M1 < 10.0.7	10.0.7
org.apache.tomcat:tomcat maven/org.apache.tomcat/tomcat	Maven	≥ 9.0.0-M1 < 9.0.48	9.0.48
org.apache.tomcat:tomcat maven/org.apache.tomcat/tomcat	Maven	≥ 8.5.0 < 8.5.68	8.5.68

References

NVD — CVE-2021-33037 NVD

https://nvd.nist.gov/vuln/detail/CVE-2021-33037

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/05f9e8b00f5d9251fcd3c95dcfd6cf84177f46c8

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/19d11556d0db99df291df33605f137976d152475

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/3202703e6d635e39b74262e81f0cb4bcbe2170dc

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/45d70a86a901cbd534f8f570bed2aec9f7f7b88e

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/506134f957a4be2c5b4a9334f7b3435fc954dbc1

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/8874fa02e9b36baa9ca6b226c0882c0190ca5a02

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/a2c3dc4c96168743ac0bab613709a5bbdaec41d0

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/da0e7cb093cf68b052d9175e469dbd0464441b0b

Security Fix Commit FIX COMMIT

https://github.com/apache/tomcat/commit/eee0d024c1b3171560c92eaba79dd6eb8eb11bcd

Apache Tomcat Security Information SECURITY

https://security.gentoo.org/glsa/202208-34

Apache Tomcat Security Information SECURITY

https://security.netapp.com/advisory/ntap-20210827-0007

Apache Tomcat Security Information SECURITY

https://tomcat.apache.org/security-10.html

Apache Tomcat Security Information SECURITY

https://tomcat.apache.org/security-8.html

Apache Tomcat Security Information SECURITY

https://tomcat.apache.org/security-9.html

Apache Tomcat Security Information SECURITY

https://www.debian.org/security/2021/dsa-4952

Apache Tomcat Security Information SECURITY

https://www.oracle.com//security-alerts/cpujul2021.html

Apache Tomcat Security Information SECURITY

https://www.oracle.com/security-alerts/cpuapr2022.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/cpuoct2021.html

lists.debian.org/debian-lts-announce... WEB

https://lists.debian.org/debian-lts-announce/2021/08/msg00009.html

lists.apache.org/thread/kovg1bft77xo... WEB

https://lists.apache.org/thread/kovg1bft77xo34ksrcskh5nl50p69962

lists.apache.org/thread.html/rf1b54f... WEB

https://lists.apache.org/thread.html/rf1b54fd3f52f998ca4829159a88cc4c23d6cef5c6447d00948e75c97@%3Ccommits.tomee.apache.org%3E

lists.apache.org/thread.html/re01e7e... WEB

https://lists.apache.org/thread.html/re01e7e93154e8bdf78a11a23f9686427bd3d51fc6e12c508645567b7@%3Ccommits.tomee.apache.org%3E

Apache Tomcat Source Repository REPOSITORY

https://github.com/apache/tomcat

lists.apache.org/thread.html/rd0dfea... WEB

https://lists.apache.org/thread.html/rd0dfea39829bc0606c936a16f6fca338127c86c0a1083970b45ac8d2@%3Ccommits.tomee.apache.org%3E

lists.apache.org/thread.html/rc6ef52... WEB

https://lists.apache.org/thread.html/rc6ef52453bb996a98cb45442871a1db56b7c349939e45d829bf9ae37@%3Ccommits.tomee.apache.org%3E

lists.apache.org/thread.html/r612a79... WEB

https://lists.apache.org/thread.html/r612a79269b0d5e5780c62dfd34286a8037232fec0bc6f1a7e60c9381%40%3Cannounce.tomcat.apache.org%3E

lists.apache.org/thread.html/r40f921... WEB

https://lists.apache.org/thread.html/r40f921575aee8d7d34e53182f862c45cbb8f3d898c9d4e865c2ec262@%3Ccommits.tomee.apache.org%3E

lists.apache.org/thread.html/r290aee... WEB

https://lists.apache.org/thread.html/r290aee55b72811fd19e75ac80f6143716c079170c5671b96932ed44b@%3Ccommits.tomee.apache.org%3E

kc.mcafee.com/corporate/index WEB

https://kc.mcafee.com/corporate/index?page=content&id=SB10366

Frequently Asked Questions

What is CVE-2021-33037?

CVE-2021-33037 is a security vulnerability in Apache Tomcat involving HTTP Request Smuggling in Apache Tomcat under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling').

Which Apache Tomcat versions are affected?

Affected versions include releases prior to 10.0.7, 9.0.48, 8.5.68 across affected packages: org.apache.tomcat:tomcat.

What version fixes CVE-2021-33037?

Upgrading to 10.0.7, 9.0.48, 8.5.68 (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 10.0.7, 9.0.48, 8.5.68. Upgrade your dependency to 10.0.7, 9.0.48, 8.5.68 or later.

What is the CVSS score of CVE-2021-33037?

CVE-2021-33037 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

What CWE is associated with CVE-2021-33037?

CVE-2021-33037 is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') (The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.).

How can I check Maven dependencies for CVE-2021-33037?

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

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CVSS V3

5.3 MODERATE

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 Low (I:L)

Availability None (A:N)

Vector String

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

Advisory Metadata

Source ID: GHSA-4vww-mc66-62m6
Schema Version: 1.4.0
Published: 2021-08-13 15:21
Last Modified: 2024-03-11 18:00
Database Record File: advisories/github-reviewed/2021/08/GHSA-4vww-mc66-62m6/GHSA-4vww-mc66-62m6.json