FUXA has an unauthenticated arbitrary tag value disclosure via /api/getTagValue

### Summary An authorization bypass in the /api/getTagValue endpoint allows unauthenticated access to tag values when the referenced script does not exist. ### Details The issue is caused by the combination of these code paths: - `server/api/apikeys/verify-api-or-token.js:45` sends requests without `x-api-key` to `authJwt.verifyToken(req, res, next)`. - `server/api/jwt-helper.js:46-64` creates a signed guest token when no `x-access-token` is provided: `if (!token) { token = getGuestToken(); }` and then populates `req.userId` / `req.userGroups` from that guest token. - `server/api/command/index.js:76-105` exposes `/api/getTagValue`. - `server/runtime/scripts/index.js:106-111` returns `true` when the referenced script does not exist: `if (!script) { return true; }` As a result, an unauthenticated request reaches `/api/getTagValue` as `guest`, and the authorization check is bypassed because `isAuthorisedByScriptName()` returns `true` when `sourceScriptName` is omitted or does not match a real script. The endpoint then returns arbitrary tag values by ID. ### PoC Requests to /api/getTagValue without authentication could succeed when the authorization logic evaluated a non-existent sourceScriptName as authorized.

Source published

26 May 2026 23:41:45 UTC

Source modified

26 May 2026 23:56:24 UTC

Observed 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

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

Publisher rating · HIGH