- Top reward
- $4,000
- Top severity paid
- Critical
- Assets in scope
- 1
- Public CVEs
- 53
- Last change
At a glance
What to know before you start testing.
- Pays up to $4,000
- for critical bugs.
- Report by email
- [email protected]
- Full safe harbor
- Good-faith research is authorised; no legal action.
Rewards
What HackerOne lists as the payout for each severity.
| Severity | Relative size | Reward |
|---|---|---|
| Critical |
|
$4,000 |
| High |
|
$2,000 |
| Medium |
|
$1,000 |
| Low |
|
$100 |
- Safe harbor
-
Full
Any activities conducted in a manner consistent with this policy will be considered authorized conduct and we will not initiate legal action against you.
Summarised with AI from the program policy on HackerOne, read 12 Nov 2026, and checked word for word against it. Read the original
Scope
1 asset you may test.
Products and areas 1
- Tor Browser Critical
Changes
Tracked since 11 Nov 2026. Last checked 1 hour ago.
No changes yet. When the rewards or scope move, you will see it here and in the RSS feed.
Before we tracked it
Scope and reward changes recorded before this page started tracking it.
-
Scope removed
Tor
-
Scope removed
https://gitlab.torproject.org/tpo/core/arti
Public CVEs
Published vulnerabilities in this vendor's products, from the NVD.
| CVE | Summary | Severity | Published |
|---|---|---|---|
| CVE-2026-77642 | tor before 0.4.9.9 was prone to an out-of-bounds write when parsing a consensus or detached signature with unexpected signature digest type. Impact is minor for most Tor roles, but potentially major for directory authorities. This is TROVE-2026-019. | High 7.5 | 20 Aug 2026 |
| CVE-2026-77641 | tor before 0.4.9.9 was prone to a NULL write after free when sending a CONFLUX_SWITCH cell fails. The return value of relay_send_command_from_edge() was ignored, so a send failure (which calls circuit_mark_for_close() and removes the leg via cfx_del_leg()) would go undetected, causing the caller to write to the now-freed current leg and resulting in a crash. This is TROVE-2026-017. | Medium 6.5 | 20 Aug 2026 |
| CVE-2026-77584 | Tor before 0.4.9.10 did not reject a CONFLUX_LINK cell that arrives on a circuit which already has attached streams. A malicious client could send a RELAY_COMMAND_BEGIN before the CONFLUX_LINK on the same circuit, attaching an exit stream that would later end up orphan leaving a dangling circuit back-pointer and a use-after-free (UAF) when the circuit is freed. This is TROVE-2026-025. | High 7.0 | 20 Aug 2026 |
| CVE-2026-77587 | Tor before 0.4.9.11 is prone to a use-after-free (and potential double free) of a conflux object when a recovery leg revives a conflux set whose last linked leg has already been closed. A malicious exit node could use this to crash a client. This is TROVE-2026-026. | Medium 5.9 | 20 Aug 2026 |
| CVE-2026-77638 | Tor before 0.4.9.11 is prone to a race condition where in just the right circumstances a rendezvous point could man-in-the-middle (impersonate) the onion service that the client was trying to reach. | High 8.9 | 20 Aug 2026 |
| CVE-2026-77639 | Tor before 0.4.9.9 was prone to a compression bomb bypass where an attacker could concatenate many gzip or zlib sub-streams, each just under the per-stream detection threshold, to avoid the compression bomb check entirely. This is TROVE-2026-022. | Medium 5.3 | 20 Aug 2026 |
| CVE-2026-77640 | tor before 0.4.9.9 was prone to an infinite loop when decompressing a truncated zlib/gzip stream with done=1. A truncated stream never reaches Z_STREAM_END, causing zlib to return Z_BUF_ERROR with no input remaining, which buf_add_compress() mistook for a full output buffer and retried forever. Fixed by returning TOR_COMPRESS_ERROR in that case so the caller can abort cleanly. This is TROVE-2026-0 | Low 3.7 | 20 Aug 2026 |
| CVE-2026-44601 | Tor before 0.4.9.7, when circuit queue memory pressure exists, can experience a client crash because of a double close of a circuit, aka TROVE-2026-009. | Low 3.7 | 7 May 2026 |
| CVE-2026-44602 | Tor before 0.4.9.7 has a NULL pointer dereference when a CERT cell is received out of order, aka TROVE-2026-006. | Low 3.7 | 7 May 2026 |
| CVE-2026-44603 | Tor before 0.4.9.7 has an out-of-bounds read by one byte via a malformed BEGIN cell, aka TROVE-2026-007. | Low 3.7 | 7 May 2026 |
| CVE-2026-44600 | Tor before 0.4.9.7 mishandles accounting of the conflux out-of-order queue during the clearing of a queue, aka TROVE-2026-010. | Low 3.7 | 7 May 2026 |
| CVE-2026-44599 | Tor before 0.4.9.7 can attempt or accept BEGIN_DIR via conflux legs, aka TROVE-2026-008. | Low 3.7 | 7 May 2026 |
| CVE-2026-44597 | Tor before 0.4.9.7 has an out-of-bounds read when an END, a TRUNCATE, or a TRUNCATED cell lacks a reason in its payload, aka TROVE-2026-011. | Low 3.7 | 7 May 2026 |
| 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 TROVE-2022-002. | Medium 6.5 | 14 Jan 2023 |
| CVE-2022-33903 | Tor 0.4.7.x before 0.4.7.8 allows a denial of service via the wedging of RTT estimation. | High 7.5 | 17 Jul 2022 |
| 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 hours after the local user used the product. This occurs because the product doesn't properly free mem | Medium 5.5 | 26 Feb 2022 |
| 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 destination server (or collected by a rogue site within the Tor network). | Medium 6.1 | 24 Sep 2021 |
| 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 TROVE-2021-007. | High 7.5 | 30 Aug 2021 |
| 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 inefficiency. | High 7.5 | 29 Jun 2021 |
| 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 descriptor | High 7.5 | 29 Jun 2021 |
| 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 stream. | High 7.5 | 29 Jun 2021 |
| 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 TROVE-2021-001. | High 7.5 | 19 Mar 2021 |
| 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 TROVE-2021-002. | Medium 5.3 | 19 Mar 2021 |
| 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 TROVE-2020-001. | High 7.5 | 15 Jul 2020 |
| 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 TROVE-2020-002. | High 7.5 | 23 Mar 2020 |
| 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 circuit. | High 7.5 | 23 Mar 2020 |
| 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 not a vulnerability | Medium 5.3 | 2 Feb 2020 |
| 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 packets. | High 7.5 | 24 Jan 2020 |
| 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 packets. | High 7.5 | 24 Jan 2020 |
| 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 vectors. | High 7.5 | 24 Jan 2020 |
| 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 descriptor. | High 7.5 | 24 Jan 2020 |
| 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 behavior of Firefox before 68. | Medium 5.3 | 30 Jun 2019 |
| 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" setting. | Medium 4.3 | 28 May 2019 |
| 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 scheduler. | High 7.5 | 21 Feb 2019 |
| 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 vulnerability. | Medium 4.3 | 14 Sep 2018 |
| 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 value. | Critical 9.8 | 13 Sep 2018 |
| 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 < 45.5.1. | High 7.5 | 11 Jun 2018 |
| 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 relay descriptor that is mishandled during voting. | High 7.5 | 5 Mar 2018 |
| 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 list. | High 7.5 | 5 Mar 2018 |
| 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 descriptor. | High 7.5 | 5 Dec 2017 |
| CVE-2017-16541 | Tor Browser before 7.0.9 on macOS and Linux allows remote attackers to bypass the intended anonymity feature and discover a client IP address via vectors involving a crafted web site that leverages file:// mishandling in Firefox, aka TorMoil. NOTE: Tails is unaffected. | Medium 6.5 | 4 Nov 2017 |
| CVE-2017-0380 | The rend_service_intro_established function in or/rendservice.c in Tor before 0.2.8.15, 0.2.9.x before 0.2.9.12, 0.3.0.x before 0.3.0.11, 0.3.1.x before 0.3.1.7, and 0.3.2.x before 0.3.2.1-alpha, when SafeLogging is disabled, allows attackers to obtain sensitive information by leveraging access to the log files of a hidden service, because uninitialized stack data is included in an error message a | Medium 5.9 | 18 Sep 2017 |
| CVE-2017-0377 | Tor 0.3.x before 0.3.0.9 has a guard-selection algorithm that only considers the exit relay (not the exit relay's family), which might allow remote attackers to defeat intended anonymity properties by leveraging the existence of large families. | High 7.5 | 2 Jul 2017 |
| CVE-2017-0375 | The hidden-service feature in Tor before 0.3.0.8 allows a denial of service (assertion failure and daemon exit) in the relay_send_end_cell_from_edge_ function via a malformed BEGIN cell. | High 7.5 | 9 Jun 2017 |
| CVE-2017-0376 | The hidden-service feature in Tor before 0.3.0.8 allows a denial of service (assertion failure and daemon exit) in the connection_edge_process_relay_cell function via a BEGIN_DIR cell on a rendezvous circuit. | High 7.5 | 9 Jun 2017 |
| CVE-2016-8860 | Tor before 0.2.8.9 and 0.2.9.x before 0.2.9.4-alpha had internal functions that were entitled to expect that buf_t data had NUL termination, but the implementation of or/buffers.c did not ensure that NUL termination was present, which allows remote attackers to cause a denial of service (client, hidden service, relay, or authority crash) via crafted data. | High 7.5 | 4 Jan 2017 |
| CVE-2014-5117 | Tor before 0.2.4.23 and 0.2.5 before 0.2.5.6-alpha maintains a circuit after an inbound RELAY_EARLY cell is received by a client, which makes it easier for remote attackers to conduct traffic-confirmation attacks by using the pattern of RELAY and RELAY_EARLY cells as a means of communicating information about hidden service names. | Medium 5.8 | 30 Jul 2014 |
| CVE-2012-2249 | Tor before 0.2.3.23-rc allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a renegotiation attempt that occurs after the initiation of the V3 link protocol. | Medium 5.0 | 3 Feb 2014 |
| CVE-2012-2250 | Tor before 0.2.3.24-rc allows remote attackers to cause a denial of service (assertion failure and daemon exit) by performing link protocol negotiation incorrectly. | Medium 5.0 | 3 Feb 2014 |
| CVE-2013-7295 | Tor before 0.2.4.20, when OpenSSL 1.x is used in conjunction with a certain HardwareAccel setting on Intel Sandy Bridge and Ivy Bridge platforms, does not properly generate random numbers for (1) relay identity keys and (2) hidden-service identity keys, which might make it easier for remote attackers to bypass cryptographic protection mechanisms via unspecified vectors. | Medium 4.0 | 17 Jan 2014 |
| CVE-2012-5573 | The connection_edge_process_relay_cell function in or/relay.c in Tor before 0.2.3.25 maintains circuits even if an unexpected SENDME cell arrives, which might allow remote attackers to cause a denial of service (memory consumption or excessive cell reception rate) or bypass intended flow-control restrictions via a RELAY_COMMAND_SENDME command. | Medium 5.0 | 1 Jan 2013 |
| CVE-2012-4419 | The compare_tor_addr_to_addr_policy function in or/policies.c in Tor before 0.2.2.39, and 0.2.3.x before 0.2.3.21-rc, allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a zero-valued port field that is not properly handled during policy comparison. | Medium 5.0 | 14 Sep 2012 |
| CVE-2012-4922 | The tor_timegm function in common/util.c in Tor before 0.2.2.39, and 0.2.3.x before 0.2.3.22-rc, does not properly validate time values, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a malformed directory object, a different vulnerability than CVE-2012-4419. | Medium 5.0 | 14 Sep 2012 |
Original policy
Copied from hackerone.com on 12 Nov 2026. The summaries on this page are made from it; the live page may have changed since.
The Tor Project is committed to working with security experts across the world to stay up to date with the latest security techniques. If you have discovered a security issue that you believe we should know about, we'd welcome working with you.
The Tor Project is only offering bug bounties for supported versions of two of its core products, Tor (the network daemon) and Tor Browser. Supported versions for Tor can be found at https://trac.torproject.org/projects/tor/wiki/org/teams/NetworkTeam/CoreTorReleases. For Tor Browser it's a good start to look at the latest stable, alpha, and nightly builds. The former can be found at https://www.torproject.org/download/ and nightlies can be obtained via https://nightlies.tbb.torproject.org/nightly-builds/tor-browser-builds/.
Other services (like the website, bug tracker, and server infrastructure) or products (like OONI or Orbot) are out of scope. Both Tor and Tor Browser bounties come with different tiers accompanied by a price range and some restrictions.
AI-Assisted Research & Submissions Policy
Mandatory Disclosures All submissions using AI-assisted tools (including LLMs) must explicitly disclose:
- What tooling was used
- Whether an LLM was involved
- Which LLM model(s) were used
Failure to provide this disclosure will make you ineligible for any bounty award.
Verification Standards AI-generated findings must include either a working proof-of-concept or thorough manual verification that demonstrates the issue is real and reproducible. Submissions lacking both will be classified as Not-Applicable (-5 Hacker Reputation).
Spam Classification (-10 Hacker Reputation) The following will be marked as Spam:
- LLM-generated content that is demonstrably false or hallucinated, with no legitimate security concern
- Submissions where trivial verification steps were skipped—issues a competent researcher should have validated before submission
- Reports that waste our time with obvious oversights or incomplete research
Policy Compliance All submissions must also meet HackerOne's Submission Standards on AI Research before being accepted.
Summary We welcome AI-assisted research. We don't welcome lazy applications of it. Verify your findings, disclose your tools, and you'll be fine.
Internet Bug Bounty
The Internet Bug Bounty is providing the funding for rewards offered by this program.
The project maintainers have final decision on which issues constitute security vulnerabilities. The Internet Bug Bounty Panel will respect their decision, and we ask that you do as well. It's important to keep in mind that not all submissions will qualify for a bounty, and that the decision to award a bounty is entirely at the discretion of the Panel.
Safe Harbor
Any activities conducted in a manner consistent with this policy will be considered authorized conduct and we will not initiate legal action against you. If legal action is initiated by a third party against you in connection with activities conducted under this policy, we will take steps to make it known that your actions were conducted in compliance with this policy.
Questions
If you have questions about our bug bounty program or if there are security bug reports you want to send directly to us (disqualifying them from any potential bounty), feel free to contact us via [email protected]. If you want to encrypt your mail, you can get the OpenPGP public key for this address from keys.openpgp.org. Here is the fingerprint:
835B 4E04 F6F7 4211 04C4 751A 3EF9 EF99 6604 DE41