No VulnCrest analysis published for this CVE yet. Below is the original CNA/NVD description, unmodified.
Description
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.
Exploits & detection
No public PoC or detection template found yet.
Timeline
- Published: 31 Oct 2026
- Last modified upstream: 06 Nov 2026
Sources & licenses
- CVE / CVSS / CWE
- NVD record ↗ (unmodified). This product uses the NVD API but is not endorsed or certified by the NVD. CVE® © The MITRE Corporation.
- Exploitation
- CISA KEV (CC0) · EPSS by FIRST.org
- References used for the analysis
- 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
- Analysis, summary and remediation
- © VulnCrest