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Fencer Intel
high 8.1

CVE-2026-55377 json

Logto: Account Center MFA management step-up bypass via WebAuthn registration verification

published 4mo ago modified 17d ago also EUVD-2026-43012

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

Logto is the modern, open-source auth infrastructure for SaaS and AI apps. Prior to 1.41.0, Logto's Account Center step-up check accepted any active verification record that belonged to the current user and had isVerified === true. A WebAuthn registration verification record for binding a new passkey could be created and verified with only an existing Account API bearer token, then sent in the logto-verification-id header and treated as identityVerified=true by Account Center routes, allowing MFA factor management without proving possession of an existing password, identifier, or MFA factor. This issue is fixed in version 1.41.0.

Patch / fix

Is CVE-2026-55377 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/logto-io/logto/security/advisories/GHSA-q4h3-38gc-4p4j referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected products

  • logto-io logto

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.