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7.5High

Apache Tomcat

CVE-2020-13935

The payload length in a WebSocket frame was not correctly validated in Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M1 to 9.0.36, 8.5.0 to 8.5.56 and 7.0.27 to 7.0.104. Invalid payload lengths could trigger an infinite loop. Multiple requests with invalid payload lengths could lead to a denial of service.

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.
  • FIRST's prediction model gives it a 87% chance of attack attempts being seen in the next 30 days, ranking above 99% of all known flaws.

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.

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Scoring

CVSS
7.5 (v3.1)
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-835
Assigned by
security@apache.org

Dates

Published
2020-07-14
Last modified
2026-08-25
Sources
NVD

Affected products

  • Apache Tomcat7.0.27 - 7.0.104, 8.5.0 - 8.5.56, 9.0.1 - 9.0.36, 9.0.0, 10.0.0
  • Debian Debian Linux9.0, 10.0
  • Netapp Oncommand System Manager3.0.0 - 3.1.3
  • Opensuse Leap15.1, 15.2
  • Canonical Ubuntu Linux16.04, 20.04
  • Mcafee Epolicy Orchestrator5.9.0, 5.9.1, 5.10.0
  • Oracle Agile Engineering Data Management6.2.1.0
  • Oracle Agile Product Lifecycle Management9.3.3, 9.3.5, 9.3.6
  • Oracle Blockchain Platform- 21.1.2
  • Oracle Commerce Guided Search11.3.2
  • Oracle Communications Cloud Native Core Policy1.14.0
  • Oracle Communications Instant Messaging Server10.0.1.5.0

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

References