Summary
SurrealDB: Custom API route lets authenticated callers override namespace/database scope via URL path
An authenticated user scoped to one namespace/database could invoke a custom API (DEFINE API) belonging to a different namespace/database, reaching another tenant's endpoint.
The route /api/{namespace}/{database}/{endpoint} took the namespace and database from the URL and applied them to the caller's session before the endpoint was looked up or run, without checking that the caller's authenticated scope covered them. Because a custom API handler runs with permissions disabled (definer's rights), the endpoint's own PERMISSIONS clause was the only gate, open to everyone for a PERMISSIONS FULL endpoint. The api::invoke() function was affected the same way, resolving against the session's selected namespace/database (settable via the surreal-ns / surreal-db headers or USE).
Workarounds
Users unable to patch should consider the following workarounds:
- Disable the custom API HTTP route via capabilities where it is not required.
- Treat separate deployments, not namespace/database boundaries, as the tenant isolation boundary on shared instances.
- Prefer a
PERMISSIONS WHEREclause that checks the authenticated identity overPERMISSIONS FULL(reduces exposure but does not restore the boundary).
Resources
- SurrealQL Documentation, DEFINE API
- SurrealDB Documentation, Capabilities
fix(core/api): reject cross-tenant custom API access(included in SurrealDB 3.2.0)
Acknowledgements
SurrealDB thanks sondt99 for reporting this issue.
Impact
What an attacker can do:
- With valid credentials for any one namespace/database (a
VIEWERis enough), invoke a custom API in another namespace/database by naming the victim scope in the URL. - Read data that endpoint returns, including from
PERMISSIONS NONEtables, since the handler runs with permissions disabled, or trigger any writes and side effects it performs.
What it can't do:
- Reach a scope without valid credentials for some namespace/database on the instance; this is not an unauthenticated bypass.
- Affect single-tenant deployments, or any deployment where callers already hold instance-wide (root) scope.
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
CVE-2026-63735 has a CVSS score of 8.1 (High). The vector is network-reachable, low 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. A fixed version is available (3.2.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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The namespace/database is now validated against the caller's authenticated level, which the request cannot change, before the endpoint is resolved or run. A target scope outside that level is rejected with 403 Forbidden, both at the HTTP entry point and at the dispatch step shared with api::invoke(). Root reaches any scope; namespace principals their namespace; database and record principals their exact namespace/database; anonymous callers remain governed by the endpoint's PERMISSIONS.
- Versions 3.2.0 and later are not affected by this issue.
Frequently Asked Questions
- What is CVE-2026-63735? CVE-2026-63735 is a high-severity missing authorization vulnerability in surrealdb (rust), affecting versions < 3.2.0. It is fixed in 3.2.0. The application does not perform an authorization check before performing a sensitive operation.
- How severe is CVE-2026-63735? CVE-2026-63735 has a CVSS score of 8.1 (High). 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.
- Which versions of surrealdb are affected by CVE-2026-63735? surrealdb (rust) versions < 3.2.0 is affected.
- Is there a fix for CVE-2026-63735? Yes. CVE-2026-63735 is fixed in 3.2.0. Upgrade to this version or later.
- Is CVE-2026-63735 exploitable, and should I be worried? Whether CVE-2026-63735 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
- What actually determines whether CVE-2026-63735 is exploitable, and how bad it is? 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.
- How do I fix CVE-2026-63735? Upgrade
surrealdbto 3.2.0 or later.