CVE-2026-73302: Budibase: OIDC SSO account takeover: incoming identity linked by email without checking email_verified

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.4%, percentile 36: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 36% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes @budibase/server (npm) <= 3.38.1, no fixed version listed. Check your lockfile, including transitive dependencies.

What it is

Budibase is an open-source low-code platform. Prior to 3.39.30, the OIDC flow in packages/backend-core/src/middleware/passport/sso/oidc.ts resolved an email without getEmailVerified or an emailverified requirement, and packages/backend-core/src/middleware/passport/sso/sso.ts then used users.getGlobalUserByEmail as a fallback account-linking key. An attacker who can authenticate through a configured identity provider that asserts a victim email as unverified can have a fresh provider identity merged into the victim Budibase account and inherit the victim roles. This issue is fixed in version 3.39.30.

From the GitHub advisory

Summary Budibase's OIDC SSO login links an incoming SSO identity to an existing Budibase account by email address alone, without ever checking the emailverified claim of the OIDC ID token. Budibase first tries to match the IdP sub; when that misses (any fresh attacker IdP account) it silently falls back to matching by the email claim and merges into the existing account by email, preserving that account's id and roles. Because the emailverified flag is never read, an attacker who can make a configured/trusted IdP emit a token carrying email = with emailverified = false is logged into Budibase as the victim, inheriting the victim's roles (including global admin/builder). Per OIDC Core §5.7 the email claim MUST NOT be used as an identity key unless emailverified is true; Budibase effectively delegates all account-linking trust to every configured IdP's email-verification policy while checking nothing itself. Full account takeover of any existing Budibase user, including the instance owner.

Details The OIDC verify callback extracts the email and never consults emailverified: - packages/backend-core/src/middleware/passport/sso/oidc.ts:59 — email: getEmail(profile, jwtClaims). - getEmail (oidc.ts:113-135) returns profile.json.email ->jwtClaims.email -> preferredusername. No emailverified check. - buildJwtClaims (oidc.ts:99-107) assembles claims from json.email/emails[0].value — no verification flag is read. grep -r emailverified packages/ -> 0 hits.

The email is then used as the account-linking key: - sso.authenticate(...) -> packages/backend-core/src/middleware/passport/sso/sso.ts: - :38,44 users.getById(generateGlobalUserID(details.userId)) keyed on the IdP sub; for a fresh attacker IdP account this 404s and is swallowed (:45-54). - :57-59 fallback: dbUser = await users.getGlobalUserByEmail(details.email) -> loads the victim's account (victim id + roles) purely by email (packages/backend-core/src/users/users.ts:100-124, USERBYEMAIL view, no binding to the IdP sub). - syncUser(...) (sso.ts:80,102-138) spreads ...user, preserving the victim id/tenantId/roles; only overwrites provider fields. - UserDB.save (packages/backend-core/src/users/db.ts:235): because ssoUser.id is the victim's, the id branch…

Weakness type: CWE-287.

Product: @budibase/server (npm) · Assigned by: GitHub_M · Published: 2026-08-13

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: low (any account)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.43% probability of exploitation activity in the next 30 days; percentile 36.

Timeline

• 2026-07-24 — GitHub-reviewed advisory GHSA-hp6v-6jw7-gv2f published (critical)
• 2026-08-13 — CVE record published by GitHub_M
• 2026-08-14 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-hp6v-6jw7-gv2f github.com
2. CVE.org record CVE-2026-73302 cve.org
3. NVD entry CVE-2026-73302 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

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