CVE-2026-117656

Acceptance of Extraneous Untrusted Data With Trusted Data vulnerability in the Sign in with Apple strategy in pow-auth Assent allows an unauthenticated remote attacker to impersonate another user via the user parameter of the authorization callback. Apple posts the user's name to the callback endpoint in a user form parameter that the browser submits and the client controls. Assent.Strategy.Apple.callback/2 in lib/assent/strategies/apple.ex decodes that parameter, and fetch_user/2 merges it over the claims of the verified ID token, so the unverified map wins. An attacker who completes a Sign in with Apple login with their own Apple ID and edits the user parameter can replace sub, email, and any other claim. Applications that look up, link, or authorize accounts by the returned subject or email then act on the attacker's values. This issue affects assent: from 0.1.25 before 0.3.2.

CVSS

No CVSS.

References

Link	Resource
https://cna.erlef.org/cves/CVE-2026-117656.html
https://github.com/pow-auth/assent/commit/18898bde0296152165ae470078490e5798329b1b
https://github.com/pow-auth/assent/commit/a2d331e8c51376d6c0b04a81aad31e0b4d4d64a3
https://github.com/pow-auth/assent/security/advisories/GHSA-9fr5-g44g-9526
https://osv.dev/vulnerability/EEF-CVE-2026-117656

Configurations

No configuration.

History

31 Oct 2026, 00:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-31 00:16

Updated : 2026-10-31 00:16

NVD link : CVE-2026-117656

Mitre link : CVE-2026-117656

CVE.ORG link : CVE-2026-117656

JSON object : View

Products Affected

No product.

CWE

CWE-290

Authentication Bypass by Spoofing

CWE-349

Acceptance of Extraneous Untrusted Data With Trusted Data

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