What’s Vulnerable › Vulnerabilities

CVE-2026-55370: Logto: TOTP code can be replayed within the RFC 6238 validity window (one-time use violation)

• Severity: medium (CVSS 6.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-10 · updated 2026-10-25
• Weakness: CWE-294

Description

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.

Affected products

• logto-io logto: before 1.41.0

References

• https://github.com/logto-io/logto/commit/9118867f6cbadc7291cf913beb4fede91ed5d374
• https://github.com/logto-io/logto/pull/9109
• https://github.com/logto-io/logto/releases/tag/v1.41.0
• https://github.com/logto-io/logto/security/advisories/GHSA-6wj7-c66m-6c82

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