Reachable Assertion in Tor - CVE-2021-38385
Published: August 25, 2021
Vulnerability identifier: #VU56095
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-38385
CWE-ID: CWE-617
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to a reachable assertion caused by a behavior mismatch between our batch-signature verification code and our single-signature verification code. A remote attacker can trigger assertion failure and perform a denial of service attack.
Affected software
Tor
Gentoo Linux
Fedora
tor (Debian package)
tor
net-vpn/tor
Gentoo Linux
Fedora
tor (Debian package)
tor
net-vpn/tor
How to mitigate CVE-2021-38385
Install updates from vendor's website.
Tor - addressed in versions 0.3.5.16, 0.4.5.10, 0.4.6.7
tor (Debian package) - addressed in versions 0.3.5.16-1, 0.4.5.10-1~deb11u1
tor - addressed in versions 0.3.5.16-1.el7, 0.4.5.10-1.el8, 0.4.5.10-1.fc33, 0.4.5.10-1.fc34
net-vpn/tor - update to 0.4.7.13
tor (Debian package) - addressed in versions 0.3.5.16-1, 0.4.5.10-1~deb11u1
tor - addressed in versions 0.3.5.16-1.el7, 0.4.5.10-1.el8, 0.4.5.10-1.fc33, 0.4.5.10-1.fc34
net-vpn/tor - update to 0.4.7.13