Improper Handling of Exceptional Conditions Affecting tor package, versions <0.2.9.14-1ubuntu1~16.04.3+esm1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
1.61% (73rd percentile)

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  • Snyk IDSNYK-UBUNTU1604-TOR-1611373
  • published22 Mar 2026
  • disclosed29 Jun 2021

Introduced: 29 Jun 2021

CVE-2021-34549  (opens in a new tab)
CWE-755  (opens in a new tab)

How to fix?

Upgrade Ubuntu:16.04 tor to version 0.2.9.14-1ubuntu1~16.04.3+esm1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream tor package and not the tor package as distributed by Ubuntu. See How to fix? for Ubuntu:16.04 relevant fixed versions and status.

An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-005. Hashing is mishandled for certain retrieval of circuit data. Consequently. an attacker can trigger the use of an attacker-chosen circuit ID to cause algorithm inefficiency.

CVSS Base Scores

version 3.1