Tor Security Vulnerabilities

CVE-2023-41442

An issue in Kloudq Technologies Limited Tor Equip 1.0, Tor Loco Mini 1.0 through 3.1 allows a remote attacker to execute arbitrary code via a crafted request to the MQTT...

CVE-2023-23589

The SafeSocks option in Tor before 0.4.7.13 has a logic error in which the unsafe SOCKS4 protocol can be used but not the safe SOCKS4a protocol, aka...

CVE-2009-0654

Tor 0.2.0.28, and probably 0.2.0.34 and earlier, allows remote attackers, with control of an entry router and an exit router, to confirm that a sender and receiver are communicating via vectors involving (1) replaying, (2) modifying, (3) inserting, or (4) deleting a single cell, and then observing....

CVE-2006-6893

Tor allows remote attackers to discover the IP address of a hidden service by accessing this service at a high rate, thereby changing the server's CPU temperature and consequently changing the pattern of time values visible through (1) ICMP timestamps, (2) TCP sequence numbers, and (3) TCP...

CVE-2006-3419

Tor before 0.1.1.20 uses OpenSSL pseudo-random bytes (RAND_pseudo_bytes) instead of cryptographically strong RAND_bytes, and seeds the entropy value at start-up with 160-bit chunks without reseeding, which makes it easier for attackers to conduct brute force guessing...

CVE-2006-3418

Tor before 0.1.1.20 does not validate that a server descriptor's fingerprint line matches its identity key, which allows remote attackers to spoof the fingerprint line, which might be trusted by users or other...

CVE-2006-3415

Tor before 0.1.1.20 uses improper logic to validate the "OR" destination, which allows remote attackers to perform a man-in-the-middle (MITM) attack via unspecified...

CVE-2006-3417

Tor client before 0.1.1.20 prefers entry points based on is_fast or is_stable flags, which could allow remote attackers to be preferred over nodes that are identified as more trustworthy "entry guard" (is_guard) systems by directory...

CVE-2006-3411

TLS handshakes in Tor before 0.1.1.20 generate public-private keys based on TLS context rather than the connection, which makes it easier for remote attackers to conduct brute force attacks on the encryption...

CVE-2006-3416

Tor before 0.1.1.20 kills the circuit when it receives an unrecognized relay command, which causes network circuits to be disbanded. NOTE: while this item is listed under the "Security fixes" section of the developer changelog, the developer clarified on 20060707 that this is only a self-DoS. ...

CVE-2006-3414

Tor before 0.1.1.20 supports server descriptors that contain hostnames instead of IP addresses, which allows remote attackers to arbitrarily group users by providing preferential address...

CVE-2006-3412

Tor before 0.1.1.20 does not sufficiently obey certain firewall options, which allows remote attackers to bypass intended access restrictions for dirservers, direct connections, or proxy...

CVE-2006-3413

The privoxy configuration file in Tor before 0.1.1.20, when run on Apple OS X, logs all data via the "logfile", which allows attackers to obtain potentially sensitive...

CVE-2010-0384

Tor 0.2.2.x before 0.2.2.7-alpha, when functioning as a directory mirror, does not prevent logging of the client IP address upon detection of erroneous client behavior, which might make it easier for local users to discover the identities of clients in opportunistic circumstances by reading log...

CVE-2010-0385

Tor before 0.2.1.22, and 0.2.2.x before 0.2.2.7-alpha, when functioning as a bridge directory authority, allows remote attackers to obtain sensitive information about bridge identities and bridge descriptors via a dbg-stability.txt directory...

CVE-2011-4897

Tor before 0.2.2.25-alpha, when configured as a relay without the Nickname configuration option, uses the local hostname as the Nickname value, which allows remote attackers to obtain potentially sensitive information by reading this...

CVE-2011-4894

Tor before 0.2.2.34, when configured as a bridge, uses direct DirPort access instead of a Tor TLS connection for a directory fetch, which makes it easier for remote attackers to enumerate bridges by observing DirPort...

CVE-2011-4895

Tor before 0.2.2.34, when configured as a bridge, sets up circuits through a process different from the process used by a client, which makes it easier for remote attackers to enumerate bridges by observing circuit...

CVE-2011-4896

Tor before 0.2.2.24-alpha continues to use a reachable bridge that was previously configured but is not currently configured, which might allow remote attackers to obtain sensitive information about clients in opportunistic circumstances by monitoring network traffic to the bridge...

CVE-2022-33903

Tor 0.4.7.x before 0.4.7.8 allows a denial of service via the wedging of RTT...

CVE-2021-46702

Tor Browser 9.0.7 on Windows 10 build 10586 is vulnerable to information disclosure. This could allow local attackers to bypass the intended anonymity feature and obtain information regarding the onion services visited by a local user. This can be accomplished by analyzing RAM memory even several.....

CVE-2021-39246

Tor Browser through 10.5.6 and 11.x through 11.0a4 allows a correlation attack that can compromise the privacy of visits to v2 onion addresses. Exact timestamps of these onion-service visits are logged locally, and an attacker might be able to compare them to timestamp data collected by the...

CVE-2021-38385

Tor before 0.3.5.16, 0.4.5.10, and 0.4.6.7 mishandles the relationship between batch-signature verification and single-signature verification, leading to a remote assertion failure, aka...

CVE-2021-34550

An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service...

CVE-2021-34549

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...

CVE-2021-34548

An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-003. An attacker can forge RELAY_END or RELAY_RESOLVED to bypass the intended access control for ending a...

CVE-2021-28089

Tor before 0.4.5.7 allows a remote participant in the Tor directory protocol to exhaust CPU resources on a target, aka...

CVE-2021-28090

Tor before 0.4.5.7 allows a remote attacker to cause Tor directory authorities to exit with an assertion failure, aka...

CVE-2020-1968

The Raccoon attack exploits a flaw in the TLS specification which can lead to an attacker being able to compute the pre-master secret in connections which have used a Diffie-Hellman (DH) based ciphersuite. In such a case this would result in the attacker being able to eavesdrop on all encrypted...

CVE-2020-15572

Tor before 0.4.3.6 has an out-of-bounds memory access that allows a remote denial-of-service (crash) attack against Tor instances built to use Mozilla Network Security Services (NSS), aka...

CVE-2020-10593

Tor before 0.3.5.10, 0.4.x before 0.4.1.9, and 0.4.2.x before 0.4.2.7 allows remote attackers to cause a Denial of Service (memory leak), aka TROVE-2020-004. This occurs in circpad_setup_machine_on_circ because a circuit-padding machine can be negotiated twice on the same...

CVE-2020-10592

Tor before 0.3.5.10, 0.4.x before 0.4.1.9, and 0.4.2.x before 0.4.2.7 allows remote attackers to cause a Denial of Service (CPU consumption), aka...

CVE-2020-8516

The daemon in Tor through 0.4.1.8 and 0.4.2.x through 0.4.2.6 does not verify that a rendezvous node is known before attempting to connect to it, which might make it easier for remote attackers to discover circuit information. NOTE: The network team of Tor claims this is an intended behavior and...

CVE-2015-2689

Tor before 0.2.4.26 and 0.2.5.x before 0.2.5.11 does not properly handle pending-connection resolve states during periods of high DNS load, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via crafted...

CVE-2015-2928

The Hidden Service (HS) server implementation in Tor before 0.2.4.27, 0.2.5.x before 0.2.5.12, and 0.2.6.x before 0.2.6.7 allows remote attackers to cause a denial of service (assertion failure and daemon exit) via unspecified...

CVE-2015-2929

The Hidden Service (HS) client implementation in Tor before 0.2.4.27, 0.2.5.x before 0.2.5.12, and 0.2.6.x before 0.2.6.7 allows remote servers to cause a denial of service (assertion failure and application exit) via a malformed HS...

CVE-2015-2688

buf_pullup in Tor before 0.2.4.26 and 0.2.5.x before 0.2.5.11 does not properly handle unexpected arrival times of buffers with invalid layouts, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via crafted...

CVE-2019-13075

Tor Browser through 8.5.3 has an information exposure vulnerability. It allows remote attackers to detect the browser's language via vectors involving an IFRAME element, because text in that language is included in the title attribute of a LINK element for a non-HTML page. This is related to a...

CVE-2019-12383

Tor Browser before 8.0.1 has an information exposure vulnerability. It allows remote attackers to detect the browser's UI locale by measuring a button width, even if the user has a "Don't send my language"...

CVE-2019-8955

In Tor before 0.3.3.12, 0.3.4.x before 0.3.4.11, 0.3.5.x before 0.3.5.8, and 0.4.x before 0.4.0.2-alpha, remote denial of service against Tor clients and relays can occur via memory exhaustion in the KIST cell...

CVE-2017-16639

Tor Browser on Windows before 8.0 allows remote attackers to bypass the intended anonymity feature and discover a client IP address, a different vulnerability than CVE-2017-16541. User interaction is required to trigger this...

CVE-2018-16983

NoScript Classic before 5.1.8.7, as used in Tor Browser 7.x and other products, allows attackers to bypass script blocking via the text/html;/json Content-Type...

CVE-2016-9079

A use-after-free vulnerability in SVG Animation has been discovered. An exploit built on this vulnerability has been discovered in the wild targeting Firefox and Tor Browser users on Windows. This vulnerability affects Firefox < 50.0.2, Firefox ESR < 45.5.1, and Thunderbird <...

CVE-2018-0490

An issue was discovered in Tor before 0.2.9.15, 0.3.1.x before 0.3.1.10, and 0.3.2.x before 0.3.2.10. The directory-authority protocol-list subprotocol implementation allows remote attackers to cause a denial of service (NULL pointer dereference and directory-authority crash) via a misformatted...

CVE-2018-0491

A use-after-free issue was discovered in Tor 0.3.2.x before 0.3.2.10. It allows remote attackers to cause a denial of service (relay crash) because the KIST implementation allows a channel to be added more than once in the pending...

CVE-2016-1254

Tor before 0.2.8.12 might allow remote attackers to cause a denial of service (client crash) via a crafted hidden service...

CVE-2017-8819

In Tor before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9, the replay-cache protection mechanism is ineffective for v2 onion services, aka TROVE-2017-009. An attacker can send many INTRODUCE2 cells to trigger this...

CVE-2017-8820

In Tor before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9, remote attackers can cause a denial of service (NULL pointer dereference and application crash) against directory authorities via a malformed descriptor, aka...

CVE-2017-8822

In Tor before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9, relays (that have incompletely downloaded descriptors) can pick themselves in a circuit path, leading to a degradation of anonymity, aka...

CVE-2017-8823

In Tor before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9, there is a use-after-free in onion service v2 during intro-point expiration because the expiring list is mismanaged in certain error cases, aka...