PT-2021-2516 · Tor+4 · Tor+4

Nick Mathewson + 1 · Published 2019-05-07 · Updated 2025-05-12 · CVE-2021-28089

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Tor versions prior to 0.4.5.7

Description The issue allows a remote participant in the Tor directory protocol to exhaust CPU resources on a target. This is related to an error in the resource consumption control mechanism of the Tor browser's dump desc() function. Exploitation of this issue can lead to a denial of service.

Recommendations For versions prior to 0.4.5.7, update to version 0.4.5.7 or later to resolve the issue. As a temporary workaround, consider restricting access to the Tor directory protocol to minimize the risk of exploitation.

Fix

Resource Exhaustion

Weakness Enumeration

CWE-400

Related Identifiers

ALT-PU-2019-1777

ALT-PU-2021-1492

ALT-PU-2025-6362

BDU:2021-01909

CVE-2021-28089

DSA-4871-1

MGASA-2021-0180

OPENSUSE-SU-2021:0461-1

OPENSUSE-SU-2021:0474-1

OPENSUSE-SU-2021_0461-1

OPENSUSE-SU-2024:11469-1

USN-5036-1

Affected Products

Alt Linux

Linuxmint

Suse

Tor

Ubuntu

References · 58

• https://bdu.fstec.ru/vul/2021-01909 · Security Note
• https://osv.dev/vulnerability/DSA-4871-1 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-28089 · Security Note
• https://ubuntu.com/security/notices/USN-5036-1 · Vendor Advisory
• https://osv.dev/vulnerability/openSUSE-SU-2021:0461-1 · Vendor Advisory
• https://gitlab.torproject.org/tpo/core/tor/-/issues/40304 · Vendor Advisory
• https://blog.torproject.org/node/2009 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-34550 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-28090 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-34549 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-28089 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2021-28089 · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HPDXB2GZHG3VNOTWSXQ3QZVHNV76WCU5 · Vendor Advisory
• https://osv.dev/vulnerability/MGASA-2021-0180 · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/[e-mail]/message/HPDXB2GZHG3VNOTWSXQ3QZVHNV76WCU5 · Vendor Advisory