Vulnerability in Logto-Io Logto
CVE-2026-55370
Logto is the modern, open-source auth infrastructure for SaaS and AI apps. Prior to 1.41.0, Logto's existing TOTP verification accepted a successfully used TOTP code again while the code remained inside the RFC 6238 acceptance window because the verifier used otplib's stateless check with window = 1 and did not persist or compare the accepted TOTP time-step counter. An attacker who has the victim's first factor and captures a live TOTP value can replay that value to satisfy MFA during the same acceptance window. This issue is fixed in version 1.41.0.
EPSS: 0.003 (26.0th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N.
Affected products
- Logto-io Logto — versions < 1.41.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-55370?
- CVE-2026-55370 is a medium-severity vulnerability in Logto-Io Logto, classified under Authentication Bypass by Capture-replay. CVSS score: 6.4/10. Published 2026-07-10.
- How severe is CVE-2026-55370?
- Medium severity. CVSS v3 base score is 6.4 out of 10.