Vulnerability in ash_authentication (CVE-2026-49757)
Summary
Vulnerability in ash_authentication (CVE-2026-49757). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 4.14.0, 5.0.0-rc.10 or later.
Original description
The description as published by the source.
Summary
AshAuthentication's OAuth2 and OIDC family strategies matched the local user by email address rather than by the OpenID Connect iss/sub claim combination. A provider login presenting a victim's email (including an unverified, reused, or email_verified: false account) resolved to and signed in as the victim's existing local account. An unauthenticated attacker who can register an account on any accepted OAuth provider with the victim's email obtains the victim's full local privileges.
Details
Per OpenID Connect Core §5.7, only the iss/sub claim combination uniquely and stably identifies an end-user; any other claim, including email, MUST NOT be used as a unique identifier. AshAuthentication's OAuth2/OIDC register flow nonetheless drove the upsert by the email field (upsert_identity on email, or a user-defined sign-in filter), and the sign-in preparation filtered users by email.
1. Provider login. The attacker signs in to a configured OAuth/OIDC provider with the victim's email. This is trivial for providers that don't verify email ownership, and possible under email-reuse / reclamation for providers that do.
2. AshAuthentication register step. 'Elixir.AshAuthentication.Strategy.OAuth2.IdentityChange':change/3 invokes the upsert action whose upsert_identity resolves on the email. The action lands on the victim's existing record.
3. Sign-in preparation. 'Elixir.AshAuthentication.Strategy.OAuth2.SignInPreparation':prepare/3 do…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49757 has been found in ash_authentication.
Risk of unauthorized operations or information disclosure.
What to do: upgrade ash_authentication to 4.14.0, 5.0.0-rc.10 or later.
If unsure, ask your IT team or search "ash_authentication CVE-2026-49757" on the vendor's site.
CVE-2026-49757 (ash_authentication) — CWE-290
Patched: 4.14.0, 5.0.0-rc.10 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-290) exists in ash_authentication.
Check the vendor advisory for the affected versions of ash_authentication.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 4.14.0, 5.0.0-rc.10.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'ash_authentication' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'ash_authentication' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
ash_authenticationを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade ash_authentication to 4.14.0, 5.0.0-rc.10ステージング環境で 4.14.0, 5.0.0-rc.10 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package hex.pm
- package github.com
- web cna.erlef.org
- web github.com
- web github.com
- web github.com
- web osv.dev
- web github.com
- web github.com
- web github.com