How severe is CVE-2021-43466?

CVE-2021-43466 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-43466?

CVE-2021-43466 affects the following packages: org.thymeleaf:thymeleaf-spring5 (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-43466?

Update org.thymeleaf:thymeleaf-spring5 to 3.0.13.RELEASE or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43466 is resolved across your whole dependency graph.

How do I detect CVE-2021-43466 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.thymeleaf:thymeleaf-spring5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-43466 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2021-43466 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-43466, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-43466?

CVE-2021-43466 has an EPSS (Exploit Prediction Scoring System) score of 4.0%, placing it in the 91th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-43466?

CVE-2021-43466 is classified as Code Injection (CWE-94). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-43466 published, and has it been updated?

CVE-2021-43466 was published on November 9, 2021 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

CRITICAL severity

CVE-2021-43466 — thymeleaf-spring5

CRITICAL

CVE-2021-43466 is a critical-severity (CVSS 9.8) Code Injection vulnerability in org.thymeleaf:thymeleaf-spring5. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.thymeleaf:thymeleaf-spring5 — see the affected versions and patch details below.

Template injection in thymeleaf-spring5

Also known asGHSA-qcj6-jqrg-4wp2

Published

Nov 9, 2021

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

4.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs91th percentile — riskier than 91% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕org.thymeleaf:thymeleaf-spring5

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.thymeleaf:thymeleaf-spring5`	all versions	3.0.13.RELEASE`org.thymeleaf:thymeleaf-spring5:3.0.13.RELEASE`

Affected Products

1 product · 1 configurations

Application

thymeleafthymeleaf

1 version

3.0.12

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

In the thymeleaf-spring5:3.0.12 component, thymeleaf combined with speci…

gitee.comNVDNov 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.thymeleaf:thymeleaf-spring5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.thymeleaf:thymeleaf-spring5 to 3.0.13.RELEASE or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43466 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Frequently Asked Questions

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

O3 Security · Impact-Aware SCA

Is CVE-2021-43466 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

9.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Raw vector

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

CWE Classification

CWE-94Code Injection

Weaponization

No Nuclei template or Metasploit module yet. 1 public proof-of-concept reference is listed on this page.

OpenSSF Scorecard

Package health score

thymeleaf-spring

2.8/10

Code-Review0/10

Maintained0/10

Branch-Protection0/10

Assessed Nov 2, 2026

Timeline

Disclosed

Nov 9, 2021

First exploit

Nov 17, 2021

Last updated

Oct 24, 2026

Identifiers

CVE-2021-43466

GHSA-qcj6-jqrg-4wp2

References

Advisorysecurity.netapp.com · ntap 20221014 0001 Advisoryvuldb.com Advisorynvd.nist.gov · CVE 2021 43466 Webgithub.com Websecurity.netapp.com · ntap 20221014 0001 Packagegithub.com · thymeleaf spring Evidencegitee.com · index

Related vulnerabilities

Also affects thymeleaf-spring5

This CVE is critical severity, in line with the other 3 CVEs affecting thymeleaf-spring5.

CVE-2026-41901CVE-2026-40477CVE-2026-40478

Same weakness: CWE-94

This CVE is critical severity; 2 of 5 other CVEs with CWE-94 are rated as high or higher (top: critical).

CVE-2026-62284CVE-2026-61536CVE-2026-44267CVE-2026-44266CVE-2026-115878Browse all CWE-94

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026

CVE-2021-43466 — thymeleaf-spring5

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2021-43466 in your dependencies?