Budibase: Webhook schema endpoint authorization bypass allows unauthenticated mutation of webhook and automation schema

CISA KEV lists vulnerabilities known to be exploited. FIRST EPSS estimates the likelihood of exploitation in the next 30 days. An unavailable score does not mean zero risk.

No exploitation or prediction data is available here for these CVEs. This does not mean they are safe or unlikely to be exploited.

Budibase is an open-source low-code platform. Prior to 3.39.0, the webhook schema-building endpoint is registered under builderRoutes, but the generic authorization middleware skips authorization for all paths matching /api/webhooks/schema. As a result, an unauthenticated caller can update the body schema for a known webhook and mutate the corresponding automation trigger output schema. This vulnerability is fixed in 3.39.0.

Source published

27 May 2026 16:57:36 UTC

Source modified

28 May 2026 14:12:26 UTC

Saved here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Budibase is an open-source low-code platform. Prior to 3.39.0, the webhook schema-building endpoint is registered under builderRoutes, but the generic authorization middleware skips authorization for all paths matching /api/webhooks/schema. As a result, an unauthenticated caller can update the body schema for a known webhook and mutate the corresponding automation trigger output schema. This vulnerability is fixed in 3.39.0.

Source published

May 27, 2026, 4:57:36 PM (timezone not stated)

Source modified

May 28, 2026, 2:12:26 PM (timezone not stated)

Saved here

13 Nov 2026 13:58:56 UTC

Source terms

ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Budibase is an open-source low-code platform. Prior to 3.39.0, the webhook schema-building endpoint is registered under builderRoutes, but the generic authorization middleware skips authorization for all paths matching /api/webhooks/schema. As a result, an unauthenticated caller can update the body schema for a known webhook and mutate the corresponding automation trigger output schema. This vulnerability is fixed in 3.39.0.

Source published

27 May 2026 18:16:27 UTC

Source modified

17 Jun 2026 10:54:53 UTC

Saved here

25 Oct 2026 12:17:32 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

The webhook schema-building endpoint is registered under `builderRoutes`, but the generic authorization middleware skips authorization for all paths matching `/api/webhooks/schema`. As a result, an unauthenticated caller can update the body schema for a known webhook and mutate the corresponding automation trigger output schema. ### Details The route appears to be builder-only: - `packages/server/src/api/routes/webhook.ts:5-9` ```ts 5:builderRoutes 6: .get("/api/webhooks", controller.fetch) 7: .put("/api/webhooks", webhookValidator(), controller.save) 8: .delete("/api/webhooks/:id/:rev", controller.destroy) 9: .post("/api/webhooks/schema/:instance/:id", controller.buildSchema) ``` However, webhook endpoint detection explicitly includes `schema`: - `packages/server/src/middleware/utils.ts:3-9` ```ts 3:const WEBHOOK_ENDPOINTS = new RegExp( 4: "^/api/webhooks/(trigger|schema|discord|ms-teams|slack)(/|$)" 5:) 6: 7:export function isWebhookEndpoint(ctx: UserCtx): boolean { 8: const path = ctx.path || ctx.request.url.split("?")[0] 9: return WEBHOOK_ENDPOINTS.test(path) ``` The authorization middleware bypasses all webhook endpoints before checking `ctx.user` or permissions: - `packages/server/src/middleware/authorized.ts:90-99` ```ts 90: ) => 91: async (ctx: UserCtx, next: any) => { 92: // webhooks don't need authentication, each webhook unique 93: // also internal requests (between services) don't need authorized 94: if (isWebhookEndpoint(ctx) || ctx.internal) { 95: return next() 96: } 97: 98: if (!ctx.user) { 99: return ctx.throw(401, "No user info found") ``` The bypassed controller writes attacker-derived schema data to the webhook and automation trigger outputs: - `packages/server/src/api/controllers/webhook.ts:56-83` ```ts 56:export async function buildSchema( 57: ctx: Ctx<BuildWebhookSchemaRequest, BuildWebhookSchemaResponse> 58:) { 59: await context.doInWorkspaceContext(ctx.params.instance, async () => { 60: const db = context.getWorkspaceDB() 61: const webhook = await db.get<Webhook>(ctx.params.id) 62: webhook.bodySchema = toJsonSchema(ctx.request.body) 63: // update the automation outputs 64: if (webhook.action.type === WebhookActionType.AUTOMATION) { 65: let automation = await db.get<Automation>(webhook.action.target) 66: const autoOutputs = automation.definition.trigger.schema.outputs 67: let properties = webhook.bodySchema?.properties 68: // reset webhook outputs 69: autoOutputs.properties = { 70: body: autoOutputs.properties.body, 71: } 72: for (let prop of Object.keys(properties || {})) { 73: if (properties?.[prop] == null) { 74: continue 75: } 76: const def = properties[prop] 77: if (typeof def === "boolean") { 78: continue 79: } 80: autoOutputs.properties[prop] = { 81: type: def.type as AutomationIOType, 82: description: AUTOMATION_DESCRIPTION, 83: } ``` The route grouping suggests builder authorization was intended, but the global webhook bypass removes it. ### PoC Non-destructive validation approach: 1. Create a webhook-backed automation as a builder. 2. Record the workspace ID and webhook ID. 3. Log out or send no auth headers. 4. Send: ```http POST /api/webhooks/schema/<workspaceId>/<webhookId> HTTP/1.1 content-type: application/json {"unauth_schema_probe":"test"} ``` 5. Fetch the webhook as a builder and observe that `bodySchema` has changed. 6. For automation-backed webhooks, inspect the automation trigger schema outputs and observe that properties were reset/updated. ### Impact An unauthenticated attacker can modify webhook schema metadata and automation trigger output schema for known webhook IDs. This can corrupt builder-visible automation definitions, alter downstream binding behavior, and disrupt webhook-backed automation workflows.

Source published

12 Jun 2026 18:28:34 UTC

Source modified

10 Sep 2026 03:50:50 UTC

Saved here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Publisher rating · HIGH