ExpressVPN - Bug Bounty Program

Rules

ExpressVPN

ExpressVPN operates thousands of VPN servers and makes cross-platform VPN applications for all major desktop and mobile operating systems, as well as routers and browser extensions.

Security is core to our values, and we value the input of hackers acting in good faith to help us maintain a high standard for the security and privacy of our users. This includes encouraging responsible vulnerability research and disclosure. We've offered an in-house bug bounty program for years and paid out thousands of dollars to security researchers in that time. We value excellent engineering and are always looking for ways to improve the security of our products and services.

Announcement: $100,000 Bonus Award

{YWH-P6800}

At ExpressVPN, we’ve devised meticulous cybersecurity controls to keep our systems and users protected from attacks and intrusions. To ensure that our VPN software and systems meet the high standards of privacy and security that we promise to our customers, we rigorously test them in-house and invite auditors to conduct independent reviews.

As part of our external validations, we have a long-running bug bounty program, with which we invite security researchers to test our systems and receive financial rewards for any problems they find. Over the years, we have awarded tens of thousands of dollars to successful bug bounty hunters.

In addition: The first person to find and demonstrate a security-critical bug on our VPN server technology, TrustedServer, will receive a new bonus award of US$100,000.00 which is 10 times the highest reward previously offered (but not claimed) by ExpressVPN.

With this new incentive, we seek to underline our confidence in TrustedServer’s design and our commitment to providing essential privacy protections to users. Do we want someone to win the award? On the one hand, no—because that would confirm the strength of our server security. But we are also deeply invested in discovering any vulnerabilities if they exist and are keen for feedback from the community. We would be thrilled to work with and reward anyone who successfully finds a bug.

How to win it

To win the one-time $100,000 bonus, you must find and report one of the following issues on our VPN servers:

• Unauthorized access to a VPN server or remote code execution
• Vulnerabilities that:
  • Leak the real IP addresses of clients as a result of a vulnerability in our VPN servers
  • Allow an attacker to monitor user traffic on our VPN servers

The award goes to the first valid submission.
All activities must remain in scope of the TrustedServer platform. This is: 10x the highest reward previously offered (but not claimed) by ExpressVPN.

Note: In order to qualify to claim this bounty, we will require proof of impact to our user’s privacy. This will require demonstration of unauthorized access, remote code execution, IP address leakage or the ability to monitor unencrypted (non-VPN encrypted) user traffic.

With this new reward, we aim to:

• Reaffirm our confidence in TrustedServer’s design
• Emphasize our commitment to user privacy
• Encourage community participation in improving our security

Exclusions

We strive to ensure that our challenges are on a level playing field. Thus, the following individuals are not eligible to claim the bonus for the first critical finding:

• full-time or part-time employees of ExpressVPN or any other subsidiary of Kape Technologies, as well as their friends and family; and
• contractors, consultants, representatives, suppliers, vendors, or any other persons related to or otherwise affiliated with ExpressVPN

Scope Description

ExpressVPN Core Functionalities

These are production services that are actively used by ExpressVPN customers and partners.

Included assets:

• *.expressvpn.com — Wildcard includes all subdomains and their children.
• expressvpn.jobs — recruitment-related integrations
• gh-mail.expressvpn.com — Greenhouse ATS integration

ExpressVPN APIs

These are key backend systems used for authentication, service provisioning, and configuration management.

• JWKS key location: https://api.jwks.kape.com/.well-known/jwks.json
• Staging API: https://xv-cp.apis-staging.xvtest.net
• General API Usage: https://api.expressvpn.com
• Base API for other Open API spec endpoints: https://cp.expressapisv2.net

Dedicated IP (DIP) API calls go to the following endpoints:

• https://api.enc.kape.com
• https://api.dbs.kape.com
• https://api.dts.kape.com
• https://api.blts.kape.com
• https://api.pcrs.kape.com
• https://api.jwks.kape.com

Reference: You are encouraged to review our OpenAPI spec: {YWH-P6464} to understand expected behaviors and endpoints.

Browser Extensions

These extensions allow users to control the VPN from their browsers and integrate password management functionality.

Included assets:

• ExpressVPN Chrome Extension
• ExpressVPN Firefox Extension
• ExpressVPN Keys Password Manager (Chrome)

Note: Please note that fingerprinting of the browser extension is not considered rewardable, as this is an accepted risk.

Mobile Applications

These native apps provide core VPN connectivity and account features on mobile devices.

Included assets:

• ExpressVPN Android Application (Play Store)
• ExpressVPN iOS Application (App Store)

Desktop Applications

These VPN clients are designed for use on major desktop operating systems.

Included assets:

• ExpressVPN Windows Application
• ExpressVPN macOS Application
• ExpressVPN Linux Application

Lightway VPN Protocol

ExpressVPN’s in-house VPN protocol focused on speed, security, and reliability. It is open source and available in multiple implementations.

Included assets:

• Lightway (Rust) - GitHub
• WolfSSL Wrapper (Rust) - GitHub

Lightway is a VPN protocol and reference implementation.

In our threat model users deploying Lightway are responsible for defining and enforcing the network access controls appropriate for their environment. See here: https://github.com/expressvpn/lightway/blob/main/docs/faq.md#firewall-configuration

The Lightway server/client does not configure or manage firewall rules. If you are using the Lightway server/client, you are responsible for ensuring that appropriate firewall rules are in place, including (but not limited to):

• Applying any required rate limiting
• Blocking or restricting IPv6 traffic
• Preventing IPv6 traffic from bypassing the tunnel. Without proper firewall configuration, traffic may bypass the tunnel depending on system and network settings.

Consequently, network isolation, traffic enforcement, DNS leak prevention, kill switch behaviour, firewall policy, and other deployment-specific security controls are the responsibility of the integrator deploying Lightway.

WolfSSL Wrapper (Rust) in scope vulnerabilities are either:

• vulnerabilities whose root cause lies within WolfSSL-rs itself, or
• vulnerabilities affecting the version of WolfSSL currently used by WolfSSL-rs, where a fixed version of WolfSSL is available and the demonstrated impact on WolfSSL-rs.

Any vulnerability within WolfSSL should be directly reported to them.

ExpressVPN VPN Servers

ExpressVPN operates a global fleet of VPN servers that users connect to from various devices.

Important notes:

• Full list of servers is not publicly available.
• A subset is visible through ExpressVPN applications — only these are in-scope.
• Brute-forcing, scanning the entire IP space, or disrupting VPN infrastructure is strictly prohibited.

We welcome responsible testing of endpoints exposed via the official apps that reflect real-world usage.

For any submissions related to our VPN servers, please include a screenshot of the VPN application clearly showing the assigned IP address and location used during testing.

Failure to provide this evidence may result in the report being closed or marked as incomplete.

ExpressVPN Aircove & Router Firmware

Aircove is ExpressVPN’s custom VPN router with always-on protection and built-in VPN functionality.

Engineering & Testing Environments

*.xvtest.net

This is the domain for ExpressVPN's and Kape's engineering tools, CI/CD environments, and staging services.

Important notes:

• Wildcard includes all subdomains and their children.

ExpressMailGuard

This currently acts primarly as a mail relay - this means spoofing is currently possible, and will not be reward. Please focus on web application and mail relay related vulnerabilities.

Internal & Operational Infrastructure

*.xvservice.net and Subdomains

These domains are used for IT infrastructure, identity services, and deployment workflows.

Key subdomains:

• 1pw-scim.prd.iat.it.xvservice.net: SCIM for 1Password
• gatekeeper.prd.iat.it.xvservice.net: Legacy IAA service
• prd.iat.it.xvservice.net, vector.prd.iat.it.xvservice.net: Production identity management
• it.xvservice.net: VMware and IT systems

Internal SaaS & IT Domains

• *.polymoon.it, corp.polymoon.it: GlobalProtect, SaaS tools
• networkguard.com: Redirects, web integrations

Program Rules

Testing Policy & Responsible Disclosure

Please adhere to the following rules while performing research on this program:

• Denial of service (DoS) attacks on ExpressVPN applications, servers, networks or infrastructure are strictly forbidden.
• Avoid tests that could cause degradation or interruption of our services.
• Do not use automated scanners or tools that generate large amount of network traffic.
• Do not leak, copy, manipulate, or destroy any user data or files in any of our applications/servers.
• No vulnerability disclosure, full, partial or otherwise, is allowed.
• Make sure to apply hunting requirements policy (User-Agent, VPN, etc.)

General Report Processing Rules

• All reports must be complete upon submission - proof of concept, impact, and reproduction steps must be included from the outset.
• Insufficient or overly theoretical reports will be closed and will not be revisited, even if additional evidence is submitted afterward - for reasons of team efficiency, rule adherence, and fairness toward researchers who provide complete reports. If your report is closed for these reasons, we will NOT review your additional evidence. Please submit a new report.
• Well-structured reports with minor gaps (e.g. a reproduction difficulty or missing justification) will be handled collaboratively, and the team will explicitly request the needed information, which will be duly considered.
• Resubmission is possible after a closure, but only if all necessary evidence is present and the vulnerability can be demonstrated according to the program's rules. Incomplete resubmissions risk being closed with the same motives, with consequences including credit deduction.
• This policy exists to prioritize proven vulnerabilities, not to disadvantage researchers.

Reports of Credentials Exposure

In the context of this program, we do not intend to encourage, accept or reward reports of credential exposures that are not applicable to our program’s scope and identified outside of our program’s scope, such as:

• Exposed credentials in/from an out-of-scope asset/source
• Sensitive information exposed in/from an out-of-scope asset/source

To avoid encouraging dark and grey economies (e.g. credential trading, social engineering), we will not accept any report based on information not originating from a failure on our part or that of our service providers.

This includes (but is not limited to):

• Stolen credentials gathered from unidentified sources
• Credentials not applicable and not found in the in-scope assets
• Exposed secrets unrelated to program scope
• PII exposed on out-of-scope assets

Important Precautions and Limitations

As a complement to the Program’s rules and testing policy:

• DO NOT alter compromised accounts by creating, deleting or modifying any data.
• DO NOT use compromised accounts to search for post-auth vulnerabilities (they won’t be eligible anyway).
• DO NOT include Personally Identifiable Information (PII) in your report. REDACT/OBFUSCATE all PII in screenshots or payloads.
• In case of exposed credentials or secrets, limit yourself to verifying the credentials' validity.
• In case of sensitive information leaks, DO NOT extract/copy all data. Only describe and list what's visible.

Reward Eligibility

We are happy to thank everyone who submits valid reports which help us improve the security of ExpressVPN. However, only those that meet the following eligibility requirements may receive a monetary reward:

• You must be the first reporter of a vulnerability.
• The vulnerability must be a qualifying vulnerability.
• The report must contain:
  • Clear textual description of the vulnerability
  • Security impact on users and systems
  • Remediation suggestions
  • Proof of exploitation (screenshots, evidence)
  • Reproduction steps (payloads, code, commands)
• You must comply with all testing policy rules.
• You must not be a current or former employee or contractor of ExpressVPN.

Reward amounts depend on:

• Reward grid of the relevant scope
• CVSS score and risk impact analysis

Out of scope

• All domains or subdomains not listed in the above list of 'Scopes'

Qualifying vulnerabilities

• SQL Injection (SQLi)
• Cross-Site Scripting (XSS)
• Remote Code Execution (RCE)
• Insecure Direct Object Reference (IDOR)
• Horizontal and vertical privilege escalation
• Authentication bypass & broken authentication
• Business Logic Errors vulnerability with real security impact
• Local files access and manipulation (LFI, RFI, XXE, SSRF, XSPA)
• Cross-Origin Resource Sharing (CORS) with real security impact
• Cross-site Request Forgery (CSRF) with real security impact
• Open Redirect
• Exposed secrets, credentials or sensitive information on an asset under our control and affecting at least one of our scopes
• Cross-site Request Forgery (CSRF) with real security impact
• Remote silent installation of any app
• Other severe logic vulnerabilities that can be exploited remotely
• Privilege escalation vulnerabilities
• Vulnerabilities able to break the site isolation restrictions of a browser
• Arbitrary code execution or silent installation by staging MITM attacks
• Stealing of sensitive information by staging MITM attacks
• UI deception vulnerabilities that may cause actual harm

Non-qualifying vulnerabilities

• Broken Link/Social media Hijacking
• Tabnabbing
• Missing cookie flags
• Content/Text injections
• Clickjacking/UI redressing
• Denial of Service (DoS) attacks
• Recently disclosed CVEs (less than 14 days since patch release)
• CVEs without exploitable vulnerabilities and PoC
• Open ports or services without exploitable vulnerabilities and PoC
• Social engineering of staff or contractors
• Presence of autocomplete attribute on web forms
• Vulnerabilities affecting outdated browsers or platforms
• Self-XSS or XSS that cannot be used to impact other users
• Any hypothetical flaw or best practices without exploitable vulnerabilities and PoC
• SSL/TLS issues (e.g. expired certificates, best practices)
• Unexploitable vulnerabilities (e.g. Self-XSS, XSS or Open Redirect through HTTP headers...)
• Reports with attack scenarios requiring MITM or physical access to victim's device. Note that local access resulting in LPE or arbitrary code execution as a result of our product will be reviewed, but general weaknesses that require a compromised host will be rejected.
• Missing security-related HTTP headers which do not lead directly to an exploitable vulnerability and PoC
• Low severity Cross-Site Request Forgery (CSRF) (e.g. Unauthenticated / Logout / Login / Products cart updates...)
• Invalid or missing email security records (e.g. SPF, DKIM, DMARC)
• Session management issues (e.g. lack of expiration, no logout on password change, concurrent sessions)
• Disclosure of information without exploitable vulnerabilities and PoC (e.g. stack traces, path disclosure, directory listings, software versions, IP disclosure, 3rd party secrets, EXIF Metadata, Origin IP)
• Disclosure of IP as a result of attacker gaining access to an already compromised machine
• CSV injection
• Malicious file upload (e.g. EICAR files, .EXE)
• HTTP Strict Transport Security Header (HSTS)
• Subdomain takeover without a full exploitable vulnerability and PoC or not applicable to the scope
• Blind SSRF without exploitable vulnerabilities and PoC (e.g. DNS & HTTP pingback, Wordpress XMLRPC)
• Lack or bypass of rate-limiting, brute-forcing or captcha issues
• User enumeration (e.g. email, alias, GUID, phone number, common CMS endpoints)
• Weak password policies (e.g. length, complexity, reuse)
• Ability to spam users (email / SMS / direct messages flooding)
• Disclosed or misconfigured public API keys (e.g. Google Maps, Firebase, analytics tools...)
• Password reset token sent via HTTP referer to external services (e.g. analytics / ads platforms)
• Stolen secrets, credentials or information gathered from a third-party asset that we have no control over
• Exposed secrets, credentials or information on an asset under our control that are not applicable to the program’s scope
• Pre-account takeover (e.g. account creation via oAuth)
• GraphQL Introspection is enabled
• Crashing your own application
• Google API Keys (eg. Analytics, Maps)
• Lack of code obfuscation / binary protection
• Exploiting a generic Android or iOS vulnerability
• Information requiring physical access to user device
• Exploits that are only possible on rooted/jailbroken device
• Exploits that are only possible on iOS version 16 and below
• Exploits that are only possible on Android version 14 and below
• Lack of encryption on internal databases/preference files on mobile device
• Vulnerabilities affecting outdated application binaries - only exploits working on latest Android/iOS versions from the respective app stores will be accepted
• Lack of client-side protections on mobile binaries: SSL pinning/binary protection/code obfuscation/jailbreak detection/root detection/anti-debugging controls/ etc
• Browser extension fingerprinting
• Punycode / Unicode confusion account related vulnerabilities without demonstrated impact
• IDOR through unexposed UUIDs
• Issues where a low-privileged local user can access or modify the desktop application’s features or settings, interact with a session logged in by another local user, or access that user’s account information (except through privilege escalation)