Priority reviewHigh

CVE-2020-13935

Apache Tomcat, tomcat, debian linux

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.

CVSS
7.5
EPSS
86.6%
99.7% percentile
CISA KEV
Not listed
Published
2020.07.15
PRIORITY ASSESSMENT

Priority review

FIRST EPSS indicates an elevated probability of exploitation.

Known exploitationNot established by KEV
Exploit probability86.6%
Technical severityCVSS 7.5

Vulnerability overview

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.

Affected product and versions

Product
Apache Tomcat, tomcat, debian linux
Affected versions
>= 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, 7.0.27 to 7.0.104, >= 7.0.27 <= 7.0.104, >= 8.5.0 <= 8.5.56, >= 9.0.1 <= 9.0.36, 9.0.0, 10.0.0, 9.0, 10.0, >= 3.0.0 <= 3.1.3, 15.1, 15.2, 16.04, 20.04, 5.9.0, 5.9.1, 5.10.0, 6.2.1.0, 9.3.3, 9.3.5, 9.3.6
Fixed versions
21.1.2

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Apache Tomcat, tomcat, debian linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
CWE-835