Circle
By Circle Technology Services, LLC Bug bounty on HackerOne circle.com
- Top reward
- $5,000
- Top severity paid
- Critical
- Assets in scope
- 22
- Public CVEs
- 0
- Last change
At a glance
What to know before you start testing.
- Pays up to $5,000
- for critical bugs.
- Report on HackerOne
- Submit through the program page.
- Full safe harbor
- Good-faith research is authorised; no legal action.
- Replies within 5 days
- As the policy promises.
- Payment
- Proof of identity needed to get paid.
- No public write-ups
- Keep findings private.
Rewards
What HackerOne lists as the payout for each severity.
| Severity | Relative size | Reward |
|---|---|---|
| Critical |
|
$5,000 from $3,000 |
| High |
|
$3,000 from $800 |
| Medium |
|
$800 from $400 |
| Low |
|
$400 from $150 |
- Response
-
Within 5 days
| Time to first response (from report submit) | 5 days |
- Safe harbor
-
Full
Any activities conducted in a manner consistent with these Terms and Conditions 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
22 assets you may test.
Smart contracts 12
- http://github.com/circlefin/noble-cctp Critical
- https://github.com/circlefin/buidl-wallet-contracts Critical
- https://github.com/circlefin/evm-cctp-contracts Critical
- https://github.com/circlefin/evm-cpn-contracts Critical
- https://github.com/circlefin/evm-gateway-contracts Critical
- https://github.com/circlefin/evm-xreserve-contracts Critical
- https://github.com/circlefin/noble-fiattokenfactory Critical
- https://github.com/circlefin/solana-cctp-contracts Critical
- https://github.com/circlefin/solana-gateway-contracts Critical
- https://github.com/circlefin/stablecoin-evm Critical
- https://github.com/circlefin/stablecoin-near Critical
- https://github.com/circlefin/starknet-cctp Critical
Source code 6
- https://github.com/circlefin/aptos-cctp Critical
- https://github.com/circlefin/stablecoin-aptos Critical
- https://github.com/circlefin/stablecoin-starknet Critical
- https://github.com/circlefin/stablecoin-sui Critical
- https://github.com/circlefin/stablecoin-xlm Critical
- https://github.com/circlefin/sui-cctp Critical
Web 4
- api.circle.com Critical
- app.circle.com Critical
- console.circle.com Critical
- https://github.com/circlefin/stellar-cctp Critical
Rules
What the policy asks of you, and the bug types it won't reward, quoted from Circle (via HackerOne)'s policy. "We" in these lines means the program, not this site.
While testing
-
Testing should be done on app-sandbox.circle.com and api-sandbox.circle.com.
-
Please provide detailed reports and replicable steps.
-
Submit one vulnerability per report, unless you need to chain vulnerabilities to provide impact.
-
Social engineering (e.g. phishing, vishing, smishing) is strictly prohibited.
-
Make a reasonable, good faith effort to avoid privacy violations, destruction of data, and interruption or degradation of our service.
-
You need to show that you could exploit a vulnerability, but you must not actually exploit it.
-
You must be at least 18 years old.
-
If you are performing research, please use your own accounts and do not interact with others’ accounts or data.
-
Please refrain from testing on the Production environment.
-
You must only use email addresses that you own and control.
Not accepted
-
Clickjacking on pages with no sensitive actions
-
Cross-Site Request Forgery (CSRF) on unauthenticated forms or forms with no sensitive actions
-
Attacks requiring MITM or physical access to a user's device.
-
Previously known vulnerable libraries without a working Proof of Concept.
-
Comma Separated Values (CSV) injection without demonstrating a vulnerability.
-
Missing best practices in SSL/TLS configuration.
-
Any activity that could lead to the disruption of our service (DoS).
-
Content spoofing and text injection issues without showing an attack vector/without being able to modify HTML/CSS
-
Rate limiting or bruteforce issues on non-authentication endpoints
-
Missing best practices in Content Security Policy.
-
Missing HttpOnly or Secure flags on cookies
-
Missing email best practices (Invalid, incomplete or missing SPF/DKIM/DMARC records, etc.)
-
Vulnerabilities only affecting users of outdated or unpatched browsers [Less than 2 stable versions behind the latest released stable version]
-
Software version disclosure / Banner identification issues / Descriptive error messages or headers (e.g. stack traces, application or server errors).
-
Tabnabbing
-
Open redirect - unless an additional security impact can be demonstrated
-
Issues that require unlikely user interaction
Summarised with AI from the program policy on HackerOne, read 12 Nov 2026, and checked word for word against it. Read the original
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
https://github.com/circlefin/malachite
-
Scope removed
https://github.com/circlefin/arc-remote-signer
-
Scope removed
https://github.com/circlefin/arc-node
-
Scope removed
rpc.testnet.arc.network
-
Scope removed
rpc.drpc.testnet.arc.network
-
Scope removed
youtube.com (out of scope)
-
Scope removed
x.com (out of scope)
-
Scope removed
rpc.quicknode.testnet.arc.network
-
Scope removed
rpc.blockdaemon.testnet.arc.network
-
Scope added
https://github.com/circlefin/stellar-cctp
Public CVEs
Published vulnerabilities in this vendor's products, from the NVD.
No CVEs matched yet. We match NVD records by vendor name, so products sold under another name can be missing.
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.
At Circle, our mission is to raise global economic prosperity through programmable internet commerce. In support of our mission, keeping our customers’ information safe is a top priority. We recognize and appreciate the work of those in the security community who identify security vulnerabilities in our products and encourage responsible disclosure of potential security vulnerabilities as part of our Bug Bounty Program (the “Program”).
Before submitting a report to Circle, please carefully review the Program Terms and Conditions set forth below. Your participation in our Program is voluntary and subject to the below terms and conditions.
Terms and Conditions
By submitting a security bug or vulnerability to Circle, you acknowledge that you have read and agreed to the Program Terms and Conditions set forth below. By making any submission under the Program, you agree that you may not publicly disclose your findings or the contents of your submission to any third parties without Circle’s prior written consent.
Response Targets
Circle Technology Services, LLC will endeavour to meet the following response targets for ethical hackers participating in our Program:
| Type of Response | SLA in business days |
|---|---|
| Time to first response (from report submit) | 5 days |
| Time to triage (from report submit) | 10 days |
| Time to bounty (from triage) | 10 days |
| Time to Resolution | depends on severity and complexity |
If our team determines the report is valid and within the scope of our guidelines, we will make efforts to keep you informed as we work toward mitigation.
Disclosure Policy
- Do not discuss this Program or any vulnerabilities (even resolved ones) outside of the Program without express written consent from the organization.
- Follow HackerOne's disclosure guidelines.
Program Rules
- Testing should be done on app-sandbox.circle.com and api-sandbox.circle.com.
- Please provide detailed reports and replicable steps. If the report is not detailed enough to reproduce the issue, the issue will not be eligible for a reward.
- Submit one vulnerability per report, unless you need to chain vulnerabilities to provide impact.
- When duplicates occur, we only award the first report that was received (provided that it can be fully reproduced).
- Multiple vulnerabilities caused by one underlying issue will be awarded one bounty.
- Social engineering (e.g. phishing, vishing, smishing) is strictly prohibited.
- Make a reasonable, good faith effort to avoid privacy violations, destruction of data, and interruption or degradation of our service. Only interact with accounts you own or with the explicit permission of the account holder.
- You need to show that you could exploit a vulnerability, but you must not actually exploit it. You must not: access, modify, copy, download, delete, compromise or otherwise misuse others’ data; access non-public information without authorization; degrade, interrupt or deny services to our users; and/or incur loss of funds that are not your own.
- You must be at least 18 years old.
- If you are performing research, please use your own accounts and do not interact with others’ accounts or data.
- Your participation in this Program must not violate any applicable laws or regulations.
- You must not leverage the existence of a vulnerability or access to sensitive or confidential data to make threats, extortionate demands, or ransom requests.
- You will be responsible for any tax implications related to any payment you receive under the Program, as determined by the laws of your jurisdiction.
- You must not be (i) employed by Circle or any of its affiliates or (ii) an immediate family member of someone employed by Circle or any of its affiliates.
- By reporting a bug, you grant Circle and its affiliates a perpetual, irrevocable, worldwide, royalty-free license to use, copy, adapt, develop, create derivative work from, or share your submission for any purpose.
- By reporting a bug, you agree to allow HackerOne to share with Circle the personal information that you provide to HackerOne relating to your tax forms so Circle can perform compliance checks.
- Whether Circle provides any payment for, and the amount of any such payment, is solely at Circle’s discretion.
- You are prohibited from participating in the Program if you are a resident of any U.S. embargoed jurisdiction, including but not limited to Iran, North Korea, Cuba, the Crimea region, and Syria; or if you are on the U.S. Treasury Department's list of Specially Designated Nationals or the U.S. Department of Commerce Denied Persons List or Entity List. By participating in the Program, you represent and warrant that you are not located in any such country or on any such list.
- We are only able to accept reports written in English.
Test Plan
- Signup a new account on sandbox
- You must only use email addresses that you own and control.
- During signup, append "_h1" to the "First Name" and "Last Name" fields. i.g. First name:
<first_name>_h1; Last name:<last_name>_h1. - Once the account is ready, you can get your Sandbox API Key and interact with api-sandbox.circle.com
Please refrain from testing on the Production environment.
Documents
- The Sandbox Environment
- API Reference
- https://www.circle.com/en/multichain-usdc
- https://developers.circle.com/stablecoin/docs
Out of scope vulnerabilities
When reporting vulnerabilities, please consider (1) attack scenario / exploitability, and (2) security impact of the bug. The following issues are considered out of scope:
- Clickjacking on pages with no sensitive actions
- Cross-Site Request Forgery (CSRF) on unauthenticated forms or forms with no sensitive actions
- Attacks requiring MITM or physical access to a user's device.
- Previously known vulnerable libraries without a working Proof of Concept.
- Comma Separated Values (CSV) injection without demonstrating a vulnerability.
- Missing best practices in SSL/TLS configuration.
- Any activity that could lead to the disruption of our service (DoS).
- Content spoofing and text injection issues without showing an attack vector/without being able to modify HTML/CSS
- Rate limiting or bruteforce issues on non-authentication endpoints
- Missing best practices in Content Security Policy.
- Missing HttpOnly or Secure flags on cookies
- Missing email best practices (Invalid, incomplete or missing SPF/DKIM/DMARC records, etc.)
- Vulnerabilities only affecting users of outdated or unpatched browsers [Less than 2 stable versions behind the latest released stable version]
- Vulnerabilities only affecting outdated versions of mobile applications [any version that is not the current stable version] or mobile applications not directly downloaded from the Apple or Google Play App Store.
- Software version disclosure / Banner identification issues / Descriptive error messages or headers (e.g. stack traces, application or server errors).
- Public Zero-day vulnerabilities that have had an official patch for less than 1 month will be awarded on a case by case basis.
- Tabnabbing
- Open redirect - unless an additional security impact can be demonstrated
- Issues that require unlikely user interaction
Safe Harbor
Any activities conducted in a manner consistent with these Terms and Conditions 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 these Terms and Conditions, we will take steps to make it known that your actions were conducted in compliance with these Terms and Conditions.
We may modify these Terms and Conditions or end the Program at any time without notice.
Thank you for helping keep Circle and our community safe!