A bug in Tor's nodelist handling caused clients to permanently mark an exit relay as rejecting all traffic after receiving a single transient RELAY_END message, such as RESOURCELIMIT or HIBERNATING. This issue, introduced in Tor 0.2.3.1-alpha, allowed a third party to steer clients away from honest exits by exhausting an exit's sockets or sending a malicious END. The fix, which clears the 'rejects_all' flag when a new consensus is installed, is slated for the next stable release.
Why it matters This fix prevents a remote attacker from manipulating a client's usable exit set, which could otherwise lead to targeted denial of service or privacy leaks by biasing circuit selection.
The Tor Project has published Tor Browser 16.0.1 for Android, Windows, macOS, and Linux. This update includes a rebase onto Firefox 153.7.0esr, an update to Tor 0.4.9.16, and backported security fixes from Firefox 160.
Why it matters The release incorporates backported security fixes and updates to the underlying Tor and Firefox components.
The Tor Project released version 0.4.9.16 as an emergency update specifically for directory authorities. The release addresses a 'thundering herd' issue caused by new required protover values in the previous release, which was causing older clients to exit. It also includes a workaround for a bug where old clients failed to handle unparseable microdescriptors correctly when TAP keys were omitted.
Why it matters Scope and consequences remain subject to the linked upstream discussion.
Following a period of packet drops and consensus delays affecting the maatuska directory authority, Tor 0.4.9.16 was released. The release introduced consensus-method 38, which reportedly eased pressure on directory authorities and reduced traffic from maatuska. Upstream network issues that contributed to the overload were also addressed during this period.
Why it matters The release of consensus-method 38 is intended to ease pressure on directory authorities.
Tor developers merged a revert of a recent change that listed multiple protocol capabilities as required. The revert addresses issues causing clients on version 0.4.8.x or lower to get stuck in a restart loop while fetching unusable consensus. This action allows affected clients to rejoin the network and treat microdescriptions as valid.
Why it matters The revert is intended to resolve a network-wide incident where a significant number of clients were unable to connect due to consensus fetching failures.
The Arti project has an open issue titled 'Arti 2.8.0 release' which serves as an automatically scraped release checklist. The checklist includes steps for preparing confidential security patches, finalizing the changelog, and performing the release, with most items marked as complete. Post-release tasks are also listed, with some items remaining unchecked.
Why it matters Scope and consequences remain subject to the linked upstream discussion.
The Tails project has released version 7.16, which updates the bundled Tor Browser to 16.0 and the Tor client to 0.4.9.15. The release also includes a fix for OpenPGP support in Thunderbird. Users can upgrade their Tails USB sticks automatically from version 7.0 or later.
Why it matters This release provides updated security components and bug fixes for users relying on the Tails operating system for privacy.
The Tor Project has published Tor Browser 16.0 for Android, Windows, macOS, and Linux. The release updates the underlying Tor version to 0.4.9.15 and Firefox to 153.6.0esr, alongside various security and privacy adjustments such as disabling WebGPU and XSLT.
Why it matters Users should update to the latest version to receive the updated Tor and Firefox components and associated security fixes.
The Tor Project has released Tor Browser 16.0 for Desktop and Android, marking the first stable release based on Firefox ESR 153. This update includes a redesigned Settings interface, an option for generic window titles to prevent local snooping, and native support for 64-bit ARM Linux. The release also incorporates over 270 Bugzilla fixes from the annual ESR transition audit to address potential privacy and security impacts.
Why it matters This release updates the browser's core engine and introduces new privacy protections, such as generic window titles, while expanding platform support to 64-bit ARM Linux devices.
The Tor Project released version 0.4.9.15, a security update introducing new defenses against large volumes of directory requests. The release makes the HSDir flag sticky across restarts and updates directory authorities to require specific protocol capabilities, rendering Tor versions 0.4.8 and earlier incompatible with the network. Operators are advised to upgrade relays as soon as possible.
Why it matters The release includes critical DoS mitigations for relays and enforces protocol changes that will disconnect older clients from the network.
A security report identified an incorrect format string in Tor's consensus generation that the report says allowed three colluding directory authorities to prevent consensus publication. The project labeled the severity as low because exploitation requires control of multiple authorities. A comment by @arma states the issue is listed as fixed in 0.4.9.15 as of commit 407ccd28a.
Why it matters The report states that three colluding directory authorities can wedge consensus on all honest authorities, resulting in a network-wide DoS.
A security report filed via HackerOne describes a vulnerability in Arti's onion-service implementation where invalid proof-of-work requests cause unbounded growth of persistent replay logs. The report states that an unauthenticated attacker can append approximately 16 bytes of data per request without solving the proof of work, potentially leading to filesystem exhaustion and service unavailability. The issue remains open in the Arti development tracker.
Why it matters The report indicates that this vulnerability could allow an attacker to cause a denial of service against onion services by exhausting disk space, requiring operator intervention for recovery.
The Arti development team has completed the release checklist for the October 1, 2026 release. The process included merging confidential security patches from a private branch into the main branch, finalizing the changelog, and publishing the crates. A signed git tag was created to mark the release.
Why it matters This release includes confidential security patches that were merged into the main branch, indicating updates to the Arti software infrastructure.
