What is CVE-2025-56221?

CVE-2025-56221 is a critical-severity vulnerability in Ascertia Signinghub, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 9.8/10. Published 2025-10-17.

How severe is CVE-2025-56221?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2025-56221 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Ascertia Signinghub

CVE-2025-56221

A lack of rate limiting in the login mechanism of SigningHub v8.6.8 allows attackers to bypass authentication via a brute force attack.

EPSS: 0.006 (42.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Ascertia Signinghub
N/a — versions n/a

Weakness classification (CWE)

CWE-307 — Improper Restriction of Excessive Authentication Attempts

Public proof-of-concept exploits

References

cve@mitre.org (Third Party Advisory)

Frequently asked questions

What is CVE-2025-56221?: CVE-2025-56221 is a critical-severity vulnerability in Ascertia Signinghub, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 9.8/10. Published 2025-10-17.
How severe is CVE-2025-56221?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2025-56221 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.