CVE-2021-43466: Spring Framework Template Injection Vulnerability

CRITICAL
Advisory Identifier: GHSA-qcj6-jqrg-4wp2
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CVSS 9.8
CWE-94
Published
Advisory Summary

CVE-2021-43466 is a CRITICAL (CVSS 9.8) template injection vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Spring Framework libraries in the Maven ecosystem. The issue involves template injection in thymeleaf-spring5. Remediation is available by upgrading affected packages to version 3.0.13.RELEASE.

CVE-2021-43466 at a Glance

CVE Identifier CVE-2021-43466
GHSA Identifier GHSA-qcj6-jqrg-4wp2
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product Spring Framework
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 9.8

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:H/I:H/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 High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-43466

To remediate this vulnerability, upgrade all affected Spring Framework 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.thymeleaf:thymeleaf-spring5 fixed: 3.0.13.RELEASE 
<dependency>
    <groupId>org.thymeleaf</groupId>
    <artifactId>thymeleaf-spring5</artifactId>
    <version>3.0.13.RELEASE</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.thymeleaf

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-43466, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.thymeleaf

Analyze the terminal output to locate any version of Spring Framework in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.0.13.RELEASE), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.thymeleaf 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-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In Spring Framework, 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

In the thymeleaf-spring5:3.0.12 component, thymeleaf combined with specific scenarios in template injection may lead to remote code execution.

CVE-2021-43466 Affected Spring Framework Versions

1 component(s)
Fixed Versions:
3.0.13.RELEASE
Product / Package Ecosystem Affected Versions Fixed Version
org.thymeleaf:thymeleaf-spring5
maven/org.thymeleaf/thymeleaf-spring5
Maven
< 3.0.13.RELEASE
3.0.13.RELEASE

References

NVD — CVE-2021-43466 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-43466
Spring Framework Source Repository REPOSITORY
https://github.com/thymeleaf/thymeleaf-spring/issues/263#issuecomment-977199524
gitee.com/wayne_wwang/wayne_w... WEB
https://gitee.com/wayne_wwang/wayne_wwang/blob/master/2021/10/31/ruoyi+thymeleaf-rce/index.html
Spring Framework Source Repository REPOSITORY
https://github.com/thymeleaf/thymeleaf-spring
Spring Framework Security Information SECURITY
https://security.netapp.com/advisory/ntap-20221014-0001
vuldb.com/ WEB
https://vuldb.com/?id.186365

Frequently Asked Questions

What is CVE-2021-43466?
CVE-2021-43466 is a security vulnerability in Spring Framework involving Template injection in thymeleaf-spring5 under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which Spring Framework versions are affected?
Affected versions include releases prior to 3.0.13.RELEASE across affected packages: org.thymeleaf:thymeleaf-spring5.
What version fixes CVE-2021-43466?
Upgrading to 3.0.13.RELEASE (or the latest patched release for your respective branch) resolves the vulnerability.
Is thymeleaf-spring5 affected?
Yes, org.thymeleaf:thymeleaf-spring5 is affected in releases prior to 3.0.13.RELEASE. Upgrade your dependency to 3.0.13.RELEASE or later.
What is the CVSS score of CVE-2021-43466?
CVE-2021-43466 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-43466?
CVE-2021-43466 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check Maven dependencies for CVE-2021-43466?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.thymeleaf'. 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-qcj6-jqrg-4wp2",
  "modified" : "2021-11-18T15:13:02Z",
  "published" : "2021-11-10T19:52:33Z",
  "aliases" : [ "CVE-2021-43466" ],
  "summary" : "Template injection in thymeleaf-spring5",
  "details" : "In the thymeleaf-spring5:3.0.12 component, thymeleaf combined with specific scenarios in template injection may lead to remote code execution.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.thymeleaf:thymeleaf-spring5"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.0.13.RELEASE"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.0.12.RELEASE"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-43466"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/thymeleaf/thymeleaf-spring/issues/263#issuecomment-977199524"
  }, {
    "type" : "WEB",
    "url" : "https://gitee.com/wayne_wwang/wayne_wwang/blob/master/2021/10/31/ruoyi+thymeleaf-rce/index.html"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/thymeleaf/thymeleaf-spring"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20221014-0001"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/?id.186365"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-11-10T18:12:25Z",
    "nvd_published_at" : "2021-11-09T12:15:00Z"
  }
}