CVE-2021-33037
Incorrect Transfer-Encoding handling with HTTP/1.0
Description
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.
How to fix CVE-2021-33037
To remediate CVE-2021-33037, upgrade the affected package to a fixed version below.
- —upgrade to 8.5.67 or later
- —upgrade to 9.0.43-2~deb11u1 or later
- —upgrade to 10.0.7 or later
Is CVE-2021-33037 being exploited?
Likely — EPSS is 75.4%, placing CVE-2021-33037 in the top tier of vulnerabilities by exploitation probability. Prioritise patching.
Affected packages (3)
- >= 8.5.0, < 8.5.67, >= 9.0.0, < 9.0.47, >= 10.0.0, < 10.0.7
- from 0, < 9.0.43-2~deb11u1
- >= 10.0.0-M1, < 10.0.7
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |