The Tor Project has released Tor Browser version 13.5.2, a critical security update that addresses three high-severity vulnerabilities and introduces enhanced circuit protection mechanisms designed to defend against advanced traffic analysis attacks. This update is mandatory for all users of Torzon Market and other darknet services.
Key Security Improvements
The headline feature of 13.5.2 is the implementation of adaptive circuit timeout resistance, a sophisticated defense against correlation attacks that attempt to de-anonymize users by measuring timing patterns between Tor entry and exit nodes. According to the Tor Project's security advisory published on January 17, 2026, this vulnerability affected all previous versions and could theoretically allow a well-resourced adversary (nation-state level) to correlate user sessions with origin IP addresses under specific network conditions.
The new protection works by introducing random timing jitter and circuit padding at the network layer, making it exponentially more difficult for attackers to perform timing analysis. In laboratory tests conducted by academic researchers at the University of Cambridge Cybersecurity Lab, the new protection reduced successful correlation attacks by 87% compared to Tor Browser 13.5.1.
Additional Updates
- Firefox ESR Base: Updated to Firefox ESR 115.7.0, including patches for five critical browser vulnerabilities (CVE-2026-0374, CVE-2026-0381, and three others)
- NoScript Update: NoScript extension updated to version 11.4.29 with improved JavaScript isolation and cross-site scripting defenses
- Tor Daemon: Core Tor routing daemon updated to 0.4.8.13, improving relay selection algorithms and guard node stability
- Memory Safety: Implementation of hardened memory allocators to defend against heap-based buffer overflow exploits
- Bridge Improvements: Enhanced obfs4 bridge support for users in censored regions like China, Iran, and Russia
Update Instructions
Tor Browser includes automatic update functionality, but we strongly recommend manually verifying the update due to the critical nature of these security patches:
- Open Tor Browser and navigate to the hamburger menu (≡) in the top-right corner
- Select "Settings" → "Tor Browser Updates"
- Click "Check for Updates" to initiate manual update check
- If version 13.5.2 is available, download and install immediately
- Restart Tor Browser to complete the update
- Verify the update by navigating to "About Tor Browser" in the menu—it should display version 13.5.2
If automatic updates fail, download the full installer from https://www.torproject.org/download/ and verify the PGP signature using the methods described in our complete access tutorial.
Implications for Torzon Market Users
For Torzon Market users, this update is not optional—it's critical. The timing correlation vulnerability could potentially be exploited to link your darknet activity to your real-world IP address, especially if you're accessing the market from a home internet connection without additional protections like VPNs or the TAILS operating system.
We strongly recommend updating immediately and reviewing your overall operational security practices. Consider using TAILS OS for maximum protection, as it includes Tor Browser updates automatically and routes all system traffic through Tor by default. For more security guidance, see our security tips page.
"The Tor Browser 13.5.2 update demonstrates why staying current with security patches is non-negotiable for darknet users. Outdated software is the #1 cause of de-anonymization." — Torzon Security Team, January 19, 2026