Vulnerability-Lookup

CVE-2026-53514 (GCVE-0-2026-53514)

Vulnerability from cvelistv5 – Published: 2026-07-15 17:30 – Updated: 2026-07-18 01:13

Title

Better Auth: Unauthorized invitation acceptance via unverified email match in organization plugin

Summary

Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, and in 1.6.14 and later when invitation IDs can be obtained outside the invited mailbox and requireEmailVerificationOnInvitation: true is not enabled, the organization plugin's acceptInvitation, rejectInvitation, getInvitation, and listUserInvitations recipient endpoints use session.user.email and an invitation ID without sufficient verified-email ownership proof, allowing a user with an unverified session for the invited email address to accept an organization invitation after obtaining the invitation ID. This issue is fixed for the original default behavior in version 1.6.11, while 1.6.14 restored compatibility for built-in opaque invitation IDs and leaves affected configurations requiring secure options.

Severity

7.7 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-18 01:12 UTC

CWE

CWE-287 - Improper Authentication
CWE-345 - Insufficient Verification of Data Authenticity
CWE-441 - Unintended Proxy or Intermediary ('Confused Deputy')
CWE-862 - Missing Authorization

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7661 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/better-auth/better-auth/securi…	x_refsource_CONFIRM
https://github.com/better-auth/better-auth/pull/9577	x_refsource_MISC
https://github.com/better-auth/better-auth/commit…	x_refsource_MISC
https://github.com/better-auth/better-auth/releas…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
better-auth	better-auth	Affected: < 1.6.11	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-53514

Vulnerability from fkie_nvd - Published: 2026-07-15 18:16 - Updated: 2026-07-21 13:41

Severity

7.7 (High) - CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/better-auth/better-auth/commit/23094a628f007f801be6d26e5b15dc5fc6fc4eb8	Patch
security-advisories@github.com	https://github.com/better-auth/better-auth/pull/9577	Issue Tracking, Patch
security-advisories@github.com	https://github.com/better-auth/better-auth/releases/tag/v1.6.11	Release Notes
security-advisories@github.com	https://github.com/better-auth/better-auth/security/advisories/GHSA-fmh4-wcc4-5jm3	Mitigation, Vendor Advisory

Impacted products

	Vendor	Product	Version
	better-auth	better_auth	*
	better-auth	better_auth	*

JSON

To clipboard

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    {
      "affectedData": [
        {
          "product": "better-auth",
          "vendor": "better-auth",
          "versions": [
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    }
  ],
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        "Vendor Advisory"
      ],
      "url": "https://github.com/better-auth/better-auth/security/advisories/GHSA-fmh4-wcc4-5jm3"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-287"
        },
        {
          "lang": "en",
          "value": "CWE-345"
        },
        {
          "lang": "en",
          "value": "CWE-441"
        },
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-FMH4-WCC4-5JM3

Vulnerability from github – Published: 2026-07-07 20:54 – Updated: 2026-07-20 19:24

Summary

Better Auth vulnerable to unauthorized invitation acceptance via unverified email match in organization plugin

Details

Am I affected?

Users are affected if all of the following are true:

Their application uses better-auth with the organization plugin (import { organization } from "better-auth/plugins/organization").
Their application enables a sign-up surface that allows arbitrary unverified email registration. Most commonly emailAndPassword: { enabled: true } without requireEmailVerification: true.
Their application has not set requireEmailVerificationOnInvitation: true on the organization() options.
Their application invitation distribution flow allows anyone other than the invited mailbox owner to obtain the invitationId. Examples: admin UI surfacing the link, copy-paste into chat, forwarded email, mail-forwarding rules at the recipient's domain, link previews logging the URL, or a custom sendInvitationEmail integration that sends to a non-owner channel.

If their application set emailAndPassword: { enabled: true, requireEmailVerification: true } so unverified rows cannot reach a usable session, they are not affected. Setting requireEmailVerificationOnInvitation: true closes acceptInvitation and rejectInvitation, but getInvitation and listUserInvitations remain ungated even with that flag.

Fix:

Upgrade to better-auth@1.6.11 or later.
If developers cannot upgrade their application, see workarounds below.

Summary

The organization plugin's acceptInvitation endpoint trusts an email-string equality check as proof that the session user owns the invited address. With Better Auth's stock emailAndPassword: { enabled: true } configuration, requireEmailVerification defaults to false, so an attacker can sign up a row keyed to victim@target.example (auto-signed-in, emailVerified: false) before the legitimate owner. When an organization admin invites that address, the attacker presents the invitationId and accepts the invitation, joining the organization at the invited role.

Details

The recipient gate compares invitation.email.toLowerCase() to session.user.email.toLowerCase() and returns 403 on mismatch. The opt-in requireEmailVerificationOnInvitation flag adds an emailVerified check, but it defaults to false and only fires on acceptInvitation and rejectInvitation; getInvitation and listUserInvitations have no emailVerified gate at all.

The bearer token (invitationId) is by default 32 chars over [a-zA-Z0-9] (~190 bits), so the realistic attack vector is leakage of the invitation link rather than brute force.

The fix shape defaults the emailVerified gate to on and extends it across all four invitation endpoints (acceptInvitation, rejectInvitation, getInvitation, listUserInvitations). This is the same trust-primitive class as GHSA-g38m-r43w-p2q7 (OAuth auto-link); both ship the rule "email equality is not ownership proof; both sides must prove ownership".

Patches

Fixed in better-auth@1.6.11. All four invitation recipient endpoints (acceptInvitation, rejectInvitation, getInvitation, listUserInvitations) now require the session user's emailVerified to be true in addition to the email-string match. The requireEmailVerificationOnInvitation option default flips from false to true, so applications are secure out of the box.

getInvitation and listUserInvitations use the new EMAIL_VERIFICATION_REQUIRED_FOR_INVITATION error code so the wording matches the operation; acceptInvitation and rejectInvitation keep the existing EMAIL_VERIFICATION_REQUIRED_BEFORE_ACCEPTING_OR_REJECTING_INVITATION code. Server-side calls to listUserInvitations that pass ctx.query.email without an authenticated session continue to bypass the gate; the gate is specific to session-authenticated recipient calls.

Integrators who intentionally accept invitations on unverified sessions can preserve the legacy permissive behavior with organization({ requireEmailVerificationOnInvitation: false }). The option is marked @deprecated; the gate at each call site carries a FIXME pointing at the next-minor follow-up that drops the option and makes the check unconditional. Operators that take this opt-out should understand the takeover risk before doing so.

Workarounds

If developers cannot upgrade their applications immediately:

Set organization({ requireEmailVerificationOnInvitation: true }). Closes acceptInvitation and rejectInvitation against unverified sessions. Does not close getInvitation or listUserInvitations.
Set emailAndPassword.requireEmailVerification: true (or remove email/password sign-up entirely). Closes the pre-registration step itself.
Layer middleware on the organization invitation routes that asserts session.user.emailVerified === true and rejects otherwise.

Impact

Account takeover via pre-account hijacking on the org invitation surface: the attacker, holding only an unverified self-issued session and the leaked invitationId, joins the organization as a member at the invited role.
Organization membership reach: the attacker reads invitation contents and any organization-scoped data the joined role can see, and acts as a member of the victim organization.

Credit

Reported by @widavies.

Resources

Severity

7.7 (High)


                  
                    CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "better-auth"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.6.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-53514"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-287",
      "CWE-345",
      "CWE-441",
      "CWE-862"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-07T20:54:51Z",
    "nvd_published_at": "2026-07-15T18:16:47Z",
    "severity": "HIGH"
  },
  "details": "### Am I affected?\n\nUsers are affected if all of the following are true:\n\n- Their application uses `better-auth` with the `organization` plugin (`import { organization } from \"better-auth/plugins/organization\"`).\n- Their application enables a sign-up surface that allows arbitrary unverified email registration. Most commonly `emailAndPassword: { enabled: true }` without `requireEmailVerification: true`.\n- Their application has not set `requireEmailVerificationOnInvitation: true` on the `organization()` options.\n- Their application invitation distribution flow allows anyone other than the invited mailbox owner to obtain the `invitationId`. Examples: admin UI surfacing the link, copy-paste into chat, forwarded email, mail-forwarding rules at the recipient\u0027s domain, link previews logging the URL, or a custom `sendInvitationEmail` integration that sends to a non-owner channel.\n\nIf their application set `emailAndPassword: { enabled: true, requireEmailVerification: true }` so unverified rows cannot reach a usable session, they are not affected. Setting `requireEmailVerificationOnInvitation: true` closes `acceptInvitation` and `rejectInvitation`, but `getInvitation` and `listUserInvitations` remain ungated even with that flag.\n\nFix:\n\n1. Upgrade to `better-auth@1.6.11` or later.\n2. If developers cannot upgrade their application, see workarounds below.\n\n### Summary\n\nThe organization plugin\u0027s `acceptInvitation` endpoint trusts an email-string equality check as proof that the session user owns the invited address. With Better Auth\u0027s stock `emailAndPassword: { enabled: true }` configuration, `requireEmailVerification` defaults to `false`, so an attacker can sign up a row keyed to `victim@target.example` (auto-signed-in, `emailVerified: false`) before the legitimate owner. When an organization admin invites that address, the attacker presents the `invitationId` and accepts the invitation, joining the organization at the invited role.\n\n### Details\n\nThe recipient gate compares `invitation.email.toLowerCase()` to `session.user.email.toLowerCase()` and returns 403 on mismatch. The opt-in `requireEmailVerificationOnInvitation` flag adds an `emailVerified` check, but it defaults to `false` and only fires on `acceptInvitation` and `rejectInvitation`; `getInvitation` and `listUserInvitations` have no `emailVerified` gate at all.\n\nThe bearer token (`invitationId`) is by default 32 chars over `[a-zA-Z0-9]` (~190 bits), so the realistic attack vector is leakage of the invitation link rather than brute force.\n\nThe fix shape defaults the `emailVerified` gate to on and extends it across all four invitation endpoints (`acceptInvitation`, `rejectInvitation`, `getInvitation`, `listUserInvitations`). This is the same trust-primitive class as GHSA-g38m-r43w-p2q7 (OAuth auto-link); both ship the rule \"email equality is not ownership proof; both sides must prove ownership\".\n\n### Patches\n\nFixed in `better-auth@1.6.11`. All four invitation recipient endpoints (`acceptInvitation`, `rejectInvitation`, `getInvitation`, `listUserInvitations`) now require the session user\u0027s `emailVerified` to be `true` in addition to the email-string match. The `requireEmailVerificationOnInvitation` option default flips from `false` to `true`, so applications are secure out of the box.\n\n`getInvitation` and `listUserInvitations` use the new `EMAIL_VERIFICATION_REQUIRED_FOR_INVITATION` error code so the wording matches the operation; `acceptInvitation` and `rejectInvitation` keep the existing `EMAIL_VERIFICATION_REQUIRED_BEFORE_ACCEPTING_OR_REJECTING_INVITATION` code. Server-side calls to `listUserInvitations` that pass `ctx.query.email` without an authenticated session continue to bypass the gate; the gate is specific to session-authenticated recipient calls.\n\nIntegrators who intentionally accept invitations on unverified sessions can preserve the legacy permissive behavior with `organization({ requireEmailVerificationOnInvitation: false })`. The option is marked `@deprecated`; the gate at each call site carries a `FIXME` pointing at the next-minor follow-up that drops the option and makes the check unconditional. Operators that take this opt-out should understand the takeover risk before doing so.\n\n### Workarounds\n\nIf developers cannot upgrade their applications immediately:\n\n- **Set `organization({ requireEmailVerificationOnInvitation: true })`**. Closes `acceptInvitation` and `rejectInvitation` against unverified sessions. Does not close `getInvitation` or `listUserInvitations`.\n- **Set `emailAndPassword.requireEmailVerification: true`** (or remove email/password sign-up entirely). Closes the pre-registration step itself.\n- **Layer middleware** on the organization invitation routes that asserts `session.user.emailVerified === true` and rejects otherwise.\n\n### Impact\n\n- **Account takeover via pre-account hijacking on the org invitation surface**: the attacker, holding only an unverified self-issued session and the leaked `invitationId`, joins the organization as a member at the invited role.\n- **Organization membership reach**: the attacker reads invitation contents and any organization-scoped data the joined role can see, and acts as a member of the victim organization.\n\n### Credit\n\nReported by @widavies.\n\n### Resources\n\n- [CWE-287: Improper Authentication](https://cwe.mitre.org/data/definitions/287.html)\n- [CWE-345: Insufficient Verification of Data Authenticity](https://cwe.mitre.org/data/definitions/345.html)\n- [CWE-862: Missing Authorization](https://cwe.mitre.org/data/definitions/862.html)\n- [CWE-441: Unintended Proxy or Intermediary](https://cwe.mitre.org/data/definitions/441.html)",
  "id": "GHSA-fmh4-wcc4-5jm3",
  "modified": "2026-07-20T19:24:41Z",
  "published": "2026-07-07T20:54:51Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/better-auth/better-auth/security/advisories/GHSA-fmh4-wcc4-5jm3"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53514"
    },
    {
      "type": "WEB",
      "url": "https://github.com/better-auth/better-auth/pull/9577"
    },
    {
      "type": "WEB",
      "url": "https://github.com/better-auth/better-auth/commit/23094a628f007f801be6d26e5b15dc5fc6fc4eb8"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/better-auth/better-auth"
    },
    {
      "type": "WEB",
      "url": "https://github.com/better-auth/better-auth/releases/tag/v1.6.11"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Better Auth vulnerable to unauthorized invitation acceptance via unverified email match in organization plugin"
}

Sightings

Author	Source	Type	Date	Other

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Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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Action not permitted

CVE-2026-53514 (GCVE-0-2026-53514)

FKIE_CVE-2026-53514

GHSA-FMH4-WCC4-5JM3

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