CVE-2026-63203: Auth Bypass (CVSS 7.6)

Description

Logto is the modern, open-source auth infrastructure for SaaS and AI apps. From 1.31.0 until 1.42.0, the Account API handlers in packages/core/src/routes/account/third-party-tokens.ts allow a caller holding a same-user access token with only the openid scope to retrieve stored social or enterprise SSO provider access tokens through GET /api/my-account/identities/{target}/access-token or GET /api/my-account/sso-identities/{connectorId}/access-token. The handlers authenticate the user but do not require the identities scope that protects neighboring identity-detail operations, bypassing the intended Account API consent boundary. Exploitation requires federated token-set storage to be enabled and the affected user to have authenticated through a supported connector. A low-trust application can use the disclosed provider token against upstream APIs within that token's granted scopes. This issue is fixed in version 1.42.0.

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CVSS v3.1 Score

7.6

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

EPSS — Exploit Prediction

0.0031

Probability of exploitation

0.22%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-862 Missing Authorization

References

Other References

https://github.com/logto-io/logto/commit/b560d17a4da4c25da95e3c73af4485d18ab7c224 https://github.com/logto-io/logto/pull/9116 https://github.com/logto-io/logto/releases/tag/v1.42.0 https://github.com/logto-io/logto/security/advisories/GHSA-6g9q-qrx7-3jxf https://github.com/logto-io/logto/security/advisories/GHSA-6g9q-qrx7-3jxf

Frequently Asked Questions

What is CVE-2026-63203? +

Logto is the modern, open-source auth infrastructure for SaaS and AI apps. From 1.31.0 until 1.42.0, the Account API handlers in packages/core/src/routes/account/third-party-tokens.ts allow a caller holding a same-user access token with only the openid scope to retrieve stored social or enterprise SSO provider access tokens through GET /api/my-account/identities/{target}/access-token or GET /api/my-account/sso-identities/{connectorId}/access-token. The handlers authenticate the user but do not require the identities scope that protects neighboring identity-detail operations, bypassing the intended Account API consent boundary. Exploitation requires federated token-set storage to be enabled and the affected user to have authenticated through a supported connector. A low-trust application can use the disclosed provider token against upstream APIs within that token's granted scopes. This issue is fixed in version 1.42.0. It has a CVSS v3.1 base score of 7.6 (HIGH).

How severe is CVE-2026-63203? +

CVE-2026-63203 has a CVSS v3.1 score of 7.6 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0031, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-63203? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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