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 a

Acceptance of Extraneous Untrusted Data With Trusted Data vulnerability in the Sign in with Apple strategy in pow-auth Assent allows an unauthenticated remote a

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.

Description from the National Vulnerability Database, published by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

What it means for a small business

If your business uses assent, install the vendor's update. If you're not sure whether you use it, ask whoever manages your computers.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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