Security Update for Tor

tor Updated 02 Oct 2025

Summary

18/10/2016

Disclosed on

N/A

Severity

Yes i

Fix available

Unrated

Severity

Not published

CVSS Score

DLA-663-1: tor - security update. Affects tor versions < 0.2.4.27-2. Fixed in 0.2.4.27-2. How to fix ↓

Free scan

Check if this vulnerability affects your application

Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.

Check my app free

No signup required · Results in about 60 seconds

Upload your dependency manifest or SBOM

Drag & drop your file here or Browse

Java Javascript PHP Python Go Rust Ruby Dart C/C++ Elixir CycloneDX SPDX

Upload a supported dependency manifest or SBOM. No installation or source-code access required.

See supported files and SBOM formats

SBOM sbom.json · bom.json · bom.xml · *.spdx.json · *.cdx.json · *.cdx.xml

Java pom.xml · gradle.lockfile · buildscript-gradle.lockfile

Javascript package-lock.json · yarn.lock · pnpm-lock.yaml

PHP composer.lock

Python poetry.lock · requirements.txt · Pipfile.lock

Go go.mod

Rust Cargo.lock

Ruby Gemfile.lock

Dart pubspec.lock

C/C++ conan.lock

Elixir mix.lock

Enter your work email to receive your report link.

Verify your email to view the full report and start 30 days of continuous monitoring. No credit card required.

Background

Tor is an open-source software that enables anonymous communication on the internet. It allows users to browse the web and access online services without revealing their identity or location. Tor relies on a network of volunteer-operated servers to route internet traffic, providing privacy and censorship resistance. However, a vulnerability has been discovered in Tor that could be exploited by remote attackers to crash a Tor client, hidden service, relay, or authority.

Vulnerability Detail

The vulnerability in Tor arises from the incorrect handling of buffer chunks, which are treated as NUL-terminated strings. This issue can be exploited by an attacker to cause a denial of service (DoS) condition on affected systems. By sending specially crafted data, the attacker can trigger a crash in the Tor software, disrupting its functionality. This vulnerability poses a risk to the availability and reliability of Tor services.

How To Fix

Minimum fixed version

0.2.4.27-2

This is the first release that contains the fix.

sudo apt-get install --only-upgrade tor

Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →

Conclusion

In conclusion, the Tor software has been found to have a vulnerability that can be exploited by remote attackers to crash Tor services. To mitigate this vulnerability, it is crucial to update the Tor package to the fixed versions mentioned in this report. For further support on vulnerability remediation, you can contact DevNack.com.

See every vulnerability recorded for tor →