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5.3Medium

Apache Tomcat

CVE-2021-33037

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.

What this means for your business

  • It affects Apache Tomcat. It matters if your company, or a supplier that handles your data, runs it.
  • An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.

What to do

  1. 1Check whether your company or your suppliers run Apache Tomcat, and which version. The affected versions are listed further down this page.
  2. 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

Check if you’re exposedBook a call

Scoring

CVSS
5.3 (v3.1)
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-444
Assigned by
security@apache.org

Dates

Published
2021-07-12
Last modified
2026-08-25
Sources
NVD

Affected products

  • Apache Tomcat8.5.0 - 8.5.66, 9.0.0 - 9.0.46, 10.0.0 - 10.0.6
  • Apache Tomee8.0.6
  • Debian Debian Linux9.0, 10.0
  • Oracle Agile Product Lifecycle Management9.3.6
  • Oracle Communications Cloud Native Core Policy1.14.0
  • Oracle Communications Cloud Native Core Service Communication Proxy1.14.0
  • Oracle Communications Diameter Signaling Router8.0.0.0 - 8.5.0.2
  • Oracle Communications Instant Messaging Server10.0.1.5.0
  • Oracle Communications Policy Management12.5.0
  • Oracle Communications Pricing Design Center12.0.0.3.0
  • Oracle Communications Session Report Manager8.0.0 - 8.2.4.0
  • Oracle Communications Session Route Manager8.0.0 - 8.2.4

As listed in the NVD configuration data. Not a statement about your estate.

References