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CVE-2026-88952— OAuth2 sign-in attached to an existing account without an email comparison in AshAuthentication

Quick assessment

Affected
team-alembic ash_authentication
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

team-alembic 项目中的 AshAuthentication 存在身份认证不当的漏洞，允许攻击者通过将一个 OAuth2 身份关联到一个不属于该攻击者的账户，从而以其他用户的身份登录。 具体机制如下： 使用注册动作的 键来匹配现有账户，随后通过 来控制是否将传入的提供商身份与该账户关联。 仅读取提供商返回的 布尔值，从未比较提供商的邮箱值与所匹配账户的邮箱。 该检查默认账户是通过其邮箱字段匹配到的，因此在其他 条件下，此检查形同虚设。攻击者只需提供一个经过验证的邮箱，即可将其身份附加到通过其他属性匹配到的

CVSS 9.1 · Critical
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I. Basic Information for CVE-2026-88952

Vulnerability Information
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Vulnerability Title
OAuth2 sign-in attached to an existing account without an email comparison in AshAuthentication
Source: CVE Program / CVE List V5
Vulnerability Description
Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker to be signed in as another user by linking an OAuth2 identity to an account that is not theirs. AshAuthentication.Strategy.OAuth2.UserResolver.resolve/3 matches an existing account using the register action's upsert_identity keys, then gates linking the incoming provider identity to it on email_trusted?/2, which reads only the provider's email_verified boolean and never compares the provider's email value with the matched account's email. That gate assumes the account was matched by its email field, so under any other upsert_identity it is vacuous and an attacker presenting their own verified email is attached to, and issued a session for, an account matched on some other attribute. The same unguarded gate applies in OAuth2.SignInPreparation on the registration_enabled? false path, where the account is matched by the sign-in action's read filter instead. The upsert also rewrites the matched account's email to the attacker's address, so later account recovery reaches the attacker rather than the owner. This issue affects ash_authentication: from 4.14.0 before 4.15.0 and from 5.0.0-rc.10 before 5.0.0-rc.14.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
team-alembic ash_authentication 4.14.0 ~ 4.15.0 cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*
team-alembic ash_authentication 64530644f9b37ebb76ca14aeb83a77597a0034b7 ~ * cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-88952

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III. Intelligence Information for CVE-2026-88952

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Vendor Advisories for CVE-2026-88952 (2)

Other References for CVE-2026-88952 (1)

Same Patch Batch · team-alembic · 2026-09-17 · 14 CVEs total

CVE-2026-82761 9.1 CRITICAL Magic link single-use tokens replayable via TOCTOU race in AshAuthentication
CVE-2026-86533 9.1 CRITICAL Revoked session accepted because the session jti is never checked in AshAuthentication and
CVE-2026-85500 9.1 CRITICAL `require_confirmed_with` is not enforced on the action and fails open on an unreadable att
CVE-2026-91039 9.1 CRITICAL dynamic_oidc identities are not namespaced by connection in ash_authentication, allowing c
CVE-2026-82760 8.2 HIGH Superlinear base62 decoding exhausts CPU and memory in AshAuthentication API key sign-in
CVE-2026-82685 7.6 HIGH Confirmation token accepted on any record in AshAuthentication
CVE-2026-80218 7.6 HIGH Sign-in token minted for one resource accepted by another in AshAuthentication
CVE-2026-81632 7.2 HIGH Single-use sign-in token placed in a redirect query string in AshAuthenticationPhoenix
CVE-2026-78223 6.9 MEDIUM Token revocation record built from unverified JWT claims in AshAuthentication
CVE-2026-86522 6.3 MEDIUM Log injection via an unescaped password reset identity in AshAuthentication
CVE-2026-81637 2.3 LOW Replayable OAuth2 CSRF state retained after a failed callback in AshAuthentication
CVE-2026-82723 1.8 LOW Actor record with password digest stored in AshAuthentication audit log entries
CVE-2026-82759 1.8 LOW Reversible IP address pseudonymisation in AshAuthentication audit log hash mode

IV. Related Vulnerabilities

Same product: ash_authentication
Same vendor: team-alembic
Same weakness: CWE-287

V. Comments for CVE-2026-88952

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