--- title: 'USN-5036-1: Tor vulnerabilities | Ubuntu security notices' description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/notices/USN-5036-1 --- 1. [Ubuntu Security Notices](https://ubuntu.com/security/notices) 2. USN-5036-1 --- # USN-5036-1: Tor vulnerabilities Publication date 4 October 2022 Overview Several security issues were fixed in Tor. Releases [20.04 LTS](https://ubuntu.com/security/notices?release=focal) [18.04 LTS](https://ubuntu.com/security/notices?release=bionic) [16.04 LTS](https://ubuntu.com/security/notices?release=xenial) [14.04 LTS](https://ubuntu.com/security/notices?release=trusty) --- Open side navigation ## Packages * [tor](https://ubuntu.com/security/cves?package=tor) - anonymizing overlay network for TCP ## Details It was discovered that Tor incorrectly handled certain memory operations. A remote attacker could use this issue to cause a denial of service. This issue only affected Ubuntu 18.04 ESM. ([CVE-2019-8955](https://ubuntu.com/security/CVE-2019-8955)) It was discovered that Tor did not properly handle the input length to dump\_desc() function. A remote attacker could use this issue to cause a denial of service. This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. ([CVE-2021-28089](https://ubuntu.com/security/CVE-2021-28089)) It was discovered that Tor did not properly sanitize the relay nickname in dirvote\_add\_signatures\_to\_pending\_consensus() function. An attacker could possibly use this issue to cause an assertion failure and then cause a denial of service. ([CVE-2021-28090](https://ubuntu.com/security/CVE-2021-28090)) It was discovered that Tor did not properly validate the layer hint on half-open streams. A remote... --- Show more ## Update instructions In general, a standard system update will make all the necessary changes. [Learn more about how to get the fixes.](https://ubuntu.com/security/cves/about#security) The problem can be corrected by updating your system to the following package versions: | Ubuntu Release | Package Version | | --- | --- | | 20.04 LTS focal | [tor](https://launchpad.net/ubuntu/+source/tor) –  0.4.2.7-1ubuntu0.1~esm1   Ubuntu Pro | | | | 18.04 LTS bionic | [tor](https://launchpad.net/ubuntu/+source/tor) –  0.3.2.10-1ubuntu0.2~esm2   Ubuntu Pro | | | | 16.04 LTS xenial | [tor](https://launchpad.net/ubuntu/+source/tor) –  0.2.9.14-1ubuntu1~16.04.3+esm1   Ubuntu Pro | | | | 14.04 LTS trusty | [tor](https://launchpad.net/ubuntu/+source/tor) –  0.2.4.27-1ubuntu0.1+esm2   Ubuntu Pro | | | --- ### Reduce your security exposure Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines. [Get Ubuntu Pro](https://ubuntu.com/pro) ## References * [CVE-2021-38385](https://ubuntu.com/security/CVE-2021-38385) * [CVE-2021-34550](https://ubuntu.com/security/CVE-2021-34550) * [CVE-2021-34549](https://ubuntu.com/security/CVE-2021-34549) * [CVE-2021-34548](https://ubuntu.com/security/CVE-2021-34548) * [CVE-2021-28090](https://ubuntu.com/security/CVE-2021-28090) * [CVE-2021-28089](https://ubuntu.com/security/CVE-2021-28089) * [CVE-2019-8955](https://ubuntu.com/security/CVE-2019-8955)