# CVE-2025-56224: Ascertia SigningHub OTP verification bypass via brute force

Source: https://junglewise.ai/threats/cve-2025-56224-ascertia-signinghub-otp-verification-bypass-via-brute-force  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-10-20. Updated: 2026-07-05  
License: CC BY 4.0 with a link back

CVE-2025-56224 · Severity: high · CVSS 8.1 · Published 2025-10-20

SigningHub is a digital signature and document workflow platform used to securely sign and manage legal documents. A security flaw in the mobile number verification process allows an attacker to bypass identity checks by repeatedly guessing one-time passwords (OTPs) without being blocked. This could allow an unauthorized individual to impersonate a user or verify a fraudulent mobile number, potentially compromising the integrity of the document signing process.

Technologies: [Ascertia Signinghub](https://junglewise.ai/threats/technologies/signinghub). Vendors: [Ascertia](https://junglewise.ai/threats/vendors/ascertia).

## Quick answers

**Is CVE-2025-56224 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-56224 being exploited in the wild.

**How severe is CVE-2025-56224?** High severity, with a CVSS score of 8.1, published 20 October 2025.

**Which products and versions are affected?** Ascertia Signinghub <= 8.6.8.

**Is there a fix for CVE-2025-56224?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2025-56224 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2025-56224?** Check whether you run Ascertia Signinghub at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is classified as CWE-307 (Improper Restriction of Excessive Authentication Attempts) within the mobile number verification function of SigningHub. The OTP verification endpoint fails to implement rate limiting or account lockout mechanisms after multiple failed attempts. A remote attacker can exploit this by automating a high volume of OTP guesses in rapid succession to successfully verify a mobile number without knowing the actual code. This bypasses a critical identity verification step. The issue is reported to be fixed in versions subsequent to 8.6.8.

## Affected products

- Ascertia SigningHub <= 8.6.8

## Timeline

- 2025-10-20: disclosed
- 2025-10-20: advisory

## References

- [http://signinghub.com/](http://signinghub.com/)
- [https://github.com/saykino/CVE-2025-56224](https://github.com/saykino/CVE-2025-56224)

## Related threats

- [An open redirect in Ascertia SigningHub User v10.0 allows attackers to redirect users to a malicious site via a crafted URL.](https://junglewise.ai/threats/cve-2025-61166-an-open-redirect-in-ascertia-signinghub-user-v10-0-allows)
- [In Ascertia SigningHub through 8.6.8, there is a lack of rate limiting on the reset password function, leading to an…](https://junglewise.ai/threats/cve-2025-54321-in-ascertia-signinghub-through-8-6-8-there-is-a-lack-of-rate)
- [In Ascertia SigningHub through 8.6.8, there is a lack of rate limiting on the invite user function, leading to an…](https://junglewise.ai/threats/cve-2025-54320-in-ascertia-signinghub-through-8-6-8-there-is-a-lack-of-rate)
- [Ascertia SigningHub denial of service in UploadStreamDocument](https://junglewise.ai/threats/cve-2025-56223-ascertia-signinghub-denial-of-service-in-uploadstreamdocument)
- [Ascertia SigningHub improper access control in Add User API](https://junglewise.ai/threats/cve-2025-56219-ascertia-signinghub-improper-access-control-in-add-user-api)