PT-2021-4125 · Tor+4 · Tor+4

Jann Horn · Published 2021-06-16 · Updated 2025-05-12 · CVE-2021-34548

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 0.4.6.5

Description The issue is related to errors in authorization, allowing a remote attacker to cause a denial of service. An attacker can forge RELAY END or RELAY RESOLVED to bypass the intended access control for ending a stream.

Recommendations For versions prior to 0.4.6.5, update to version 0.4.6.5 or later to resolve the issue. As a temporary workaround, consider restricting access to the RELAY END and RELAY RESOLVED functions to minimize the risk of exploitation.

Fix

Authentication Bypass by Spoofing

Incorrect Authorization

Weakness Enumeration

CWE-290

CWE-863

Related Identifiers

ALT-PU-2021-2008

ALT-PU-2025-6362

BDU:2021-04716

CVE-2021-34548

DSA-4932-1

MGASA-2021-0293

OPENSUSE-SU-2021:0926-1

OPENSUSE-SU-2021:0941-1

OPENSUSE-SU-2021_0926-1

OPENSUSE-SU-2024:11469-1

USN-5036-1

Affected Products

Alt Linux

Linuxmint

Suse

Tor

Ubuntu

References · 62

• https://osv.dev/vulnerability/openSUSE-SU-2024:11469-1 · Vendor Advisory
• https://blog.torproject.org/node/2041 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-38385 · Vendor Advisory
• https://osv.dev/vulnerability/openSUSE-SU-2021:0941-1 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2021-34548 · Vendor Advisory
• https://bdu.fstec.ru/vul/2021-04716 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2021-34548 · Security Note
• https://osv.dev/vulnerability/DSA-4932-1 · Vendor Advisory
• https://advisories.mageia.org/MGASA-2021-0293.html · Security Note
• https://ubuntu.com/security/CVE-2021-34550 · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/[e-mail]/thread/RST7YTNTKJURIR2QVIJMEBXWW2YHETRX · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2021-34548 · Vendor Advisory
• https://osv.dev/vulnerability/USN-5036-1 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-34549 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-28090 · Vendor Advisory