1. Ubuntu 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

Packages

  • 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)

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)

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)

It was discovered that Tor did not properly validate the layer hint on
half-open streams. A remote...

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)

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)

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)

It was discovered that Tor did not properly validate the layer hint on
half-open streams. A remote attacker could possibly use this issue to bypass
the access control, leading to remote code execution. This issue only affected
Ubuntu 20.04 ESM. (CVE-2021-34548)

It was discovered that Tor was using an insecure hash 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-2021-34549)

It was discovered that Tor did not properly manage memory under certain
circumstances. If a user were tricked into opening a specially crafted request,
a remote attacker could possibly use this issue to cause a crash, resulting in
a denial of service, or possibly reading sensitive data. This issue only
affected Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. (CVE-2021-34550)

It was discovered that Tor mishandles the relationship between batch-signature
verification and single-signature verification. An attacker could possibly use
this issue to cause an assertion failure and then cause a denial of service.
This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM and Ubuntu 20.04
ESM. (CVE-2021-38385)

Update instructions

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
20.04 focal tor –  0.4.2.7-1ubuntu0.1~esm1  
18.04 bionic tor –  0.3.2.10-1ubuntu0.2~esm2  
16.04 xenial tor –  0.2.9.14-1ubuntu1~16.04.3+esm1  
14.04 trusty tor –  0.2.4.27-1ubuntu0.1+esm2  

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References

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