Vulnerability in Apache Tomcat (CVE-2021-33037, CVSS 5.3)

Summary

Vulnerability in Apache Tomcat (CVE-2021-33037). Risk of unauthorized operations or information disclosure.

Original description

The description as published by the source.

Apache Tomcat 10.0.0 to 10.0.6, 9.0.0 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.

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2021-33037 has been found in Apache Tomcat.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Apache Tomcat CVE-2021-33037" on the vendor's site.

CVE-2021-33037 (Apache Tomcat) — CWE-444 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-444) exists in Apache Tomcat.

📍 Affected scope

Check the vendor advisory for the affected versions of Apache Tomcat.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Tomcat' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
grep -r 'Tomcat' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で Tomcat を grep し、稼働しているサービス・バージョンを把握する。
2
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Bitnami tomcat

[{"type":"SEMVER","events":[{"introduced":"8.5.0"},{"fixed":"8.5.67"},{"introduced":"9.0.0"},{"fixed":"9.0.47"},{"introduced":"10.0.0"},{"fixed":"10.0.7"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2021-33037 tomcat9 Fixed in: 9.0.43-2
Ubuntu UBUNTU-CVE-2021-33037 tomcat6