CVE-2021-28089: High severity torproject Tor vulnerability

Published Mar 19, 2021
·
Updated

Tor before 0.4.5.7 allows a remote participant in the Tor directory protocol to exhaust CPU resources on a target, aka TROVE-2021-001.

Affected Software

23 affected componentsFixes available
torproject Tor<0.3.5.14
torproject Tor>=0.4.4.4<0.4.4.8
torproject Tor>=0.4.5.0<0.4.5.7
torproject Tor=0.4.4.0-alpha
torproject Tor=0.4.4.1-alpha
torproject Tor=0.4.4.2-alpha
torproject Tor=0.4.4.3-alpha
Fedoraproject Fedora=33
alpine/tor>=0.4.4.4<0.3.5.14-r0
0.3.5.14-r0
alpine/tor>=0.4.4.4<0.4.4.9-r0
0.4.4.9-r0
alpine/tor>=0.4.4.4<0.4.4.9-r0
0.4.4.9-r0
alpine/tor>=0.4.4.4<0.4.4.8-r0
0.4.4.8-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0
alpine/tor>=0.4.4.4<0.4.5.7-r0
0.4.5.7-r0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade alpine/tor to a version that resolves this vulnerability.

    Fixed in 0.3.5.14-r0
  2. Upgrade

    Upgrade alpine/tor to a version that resolves this vulnerability.

    Fixed in 0.4.4.9-r0
  3. Upgrade

    Upgrade alpine/tor to a version that resolves this vulnerability.

    Fixed in 0.4.4.8-r0
  4. Upgrade

    Upgrade alpine/tor to a version that resolves this vulnerability.

    Fixed in 0.4.5.7-r0

Event History

Mar 19, 2021
CVE Published
via MITRE·04:18 AM
Data Sourced
via MITRE·04:18 AM
Description
Data Sourced
via NVD·05:15 AM
DescriptionSeverityWeaknessAffected Software
Data Sourced
via OSV·05:15 AM
DescriptionSeverityAffected Software

Frequently Asked Questions

1

What is CVE-2021-28089?

CVE-2021-28089 is a vulnerability in Tor before version 0.4.5.7 that allows a remote participant in the Tor directory protocol to exhaust CPU resources on a target.

2

What is the severity of CVE-2021-28089?

The severity of CVE-2021-28089 is high with a CVSS score of 7.5.

3

What software versions are affected by CVE-2021-28089?

Versions of Tor up to and including 0.3.5.14, 0.4.4.4 to 0.4.4.8, and 0.4.5.0 to 0.4.5.7 are affected by CVE-2021-28089.

4

How can a remote participant exhaust CPU resources on a target using CVE-2021-28089?

A remote participant in the Tor directory protocol can exhaust CPU resources on a target by exploiting the vulnerability in Tor before version 0.4.5.7.

5

How can I fix CVE-2021-28089?

To fix CVE-2021-28089, update Tor to version 0.4.5.7 or later.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203