CVE-2026-41428 is a critical-severity improper authentication vulnerability in @budibase/backend-core (npm), affecting versions <= 3.35.3. No fixed version is listed yet.
Summary The authenticated middleware uses unanchored regular expressions to match public (no-auth) endpoint patterns against ctx.request.url. Since ctx.request.url in Koa includes the query string, an attacker can access any protected endpoint by appending a public endpoint path as a query parameter. For example, POST /api/global/users/search?x=/api/system/status bypasses all authentication because the regex /api/system/status/ matches in the query string portion of the URL. Details Step 1, Public endpoint patterns compiled without anchors packages/backend-core/src/middleware/matchers.ts, line 26: No ^ prefix, no $ suffix. The regex matches anywhere in the test string. Step 2, Regex tested against full URL including query string packages/backend-core/src/middleware/matchers.ts, line 32: Koa's ctx.request.url returns the full URL including query string (e.g., /api/global/users/search?x=/api/system/status). The regex /api/system/status matches in the query string. Step 3, publicEndpoint flag set to true packages/backend-core/src/middleware/authenticated.ts, lines 123-125: Step 4, Worker's global auth check skipped packages/worker/src/api/index.ts, lines 160-162: When ctx.publicEndpoint is true, the 403 check at line 165-168 is never executed. Step 5, Routes without per-route auth middleware are exposed loggedInRoutes in packages/worker/src/api/routes/endpointGroups/standard.ts line 23: Endpoints on loggedInRoutes have NO secondary auth check. The global check at index.ts:160-169 was their only protection. Affected endpoints (no per-route auth, fully exposed): POST /api/global/users/search, search all users (emails, names, roles) GET /api/global/self, get current user info GET /api/global/users/accountholder, account holder lookup GET /api/global/template/definitions, template definitions POST /api/global/license/refresh, refresh license POST /api/global/event/publish, publish events Not affected (have secondary per-route auth that blocks undefined user): GET /api/global/users, on builderOrAdminRoutes which checks isAdmin(ctx.user) → returns false for undefined → throws 403 DELETE /api/global/users/:id, on adminRoutes → same secondary check blocks it PoC Without auth → 403. With ?x=/api/system/status → returns all users. Any public endpoint pattern works as the bypass value: ?x=/api/system/status ?x=/api/system/environment ?x=/api/global/configs/public ?x=/api/global/auth/default Impact An unauthenticated attacker can: Enumerate all users, emails, names, roles, admin status, builder status via /api/global/users/search Discover account holder, identify the instance owner via /api/global/users/accountholder Trigger license refresh, potentially disrupt service via /api/global/license/refresh Publish events, inject events into the event system via /api/global/event/publish The user search is the most damaging, it reveals the full user directory of the Budibase instance to anyone on the internet. Note: endpoints on builderOrAdminRoutes and adminRoutes are NOT affected because they have secondary middleware (workspaceBuilderOrAdmin, adminOnly) that independently checks ctx.user and throws 403 when it's undefined. Only loggedInRoutes endpoints (which rely solely on the global auth check) are exposed. Suggested Fix Two options (both should be applied): Option A, Anchor the regex: Option B, Use ctx.request.path instead of ctx.request.url:
The application does not adequately verify the identity of a user, device, or process before granting access. Typical impact: unauthorized access to functions or data reserved for authenticated parties.
CVE-2026-41428 has a CVSS score of 9.1 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
npm
@budibase/backend-core (<= 3.35.3)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
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Already deployed Kodem? See CVE-2026-41428 in your environment →No fixed version is listed for CVE-2026-41428 yet.
In the interim: Keep the dependency up to date. Ensure authentication checks are present and cannot be bypassed by manipulating request parameters.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-41428 is a critical-severity improper authentication vulnerability in @budibase/backend-core (npm), affecting versions <= 3.35.3. No fixed version is listed yet. The application does not adequately verify the identity of a user, device, or process before granting access.
CVE-2026-41428 has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
@budibase/backend-core (npm) versions <= 3.35.3 is affected.
No fixed version is listed for CVE-2026-41428 yet. Monitor the advisory for updates and apply mitigations in the interim.
Whether CVE-2026-41428 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
No fixed version is listed yet. In the interim: Keep the dependency up to date. Ensure authentication checks are present and cannot be bypassed by manipulating request parameters.