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MEDIUM severity

CVE-2026-63740 — surrealdb

MEDIUMFix: surrealdb/surrealdb@8f89b26

CVE-2026-63740 is a medium-severity (CVSS 6.5) CWE-863 vulnerability in surrealdb. A fix is available for surrealdb — see the affected versions and patch details below.

SurrealDB: Array element-level (field.*) SELECT permissions leak denied elements to record users

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-63740.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs27th percentile — riskier than 27% of all scored CVEsHighest risk
0.00%0.29%0.57%0.86%0.3%0.4%0.4%0.4%Aug 26Oct 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-63740 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 383,485 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🦀surrealdb

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

A SELECT permission defined on an array element (DEFINE FIELD field.* … PERMISSIONS FOR select …) is not enforced correctly for RECORD users. Instead of hiding the denied elements, the query leaks a subset of them: a deny-all returns the odd-indexed elements, and a per-element predicate keeps and drops the wrong ones.

The filter removed each denied element by index while walking the array forwards. Because removing an element shifts every later index down, each cut invalidated the indices still pending in the loop, leaving denied elements behind. Field-level permissions are enforced correctly; only the element (field.*) level is affected, and only for record users — root and record-owner sessions are not.

Impact

What an attacker can do:

  • As a record (scope) user, read array elements that an element-level (field.*) SELECT permission should hide, on any table they can already SELECT.
  • Recover denied elements through both a deny-all and a WHERE predicate — the wrong elements are selected either way.

What it can't do:

  • Bypass field-level SELECT permissions, which are evaluated correctly.
  • Affect root or record-owner sessions, or cross namespace/database isolation.
  • Modify data, escalate privileges, or affect availability (confidentiality only).

Patches

The three permission-filtering paths (doc/reduce.rs, doc/output.rs, exec/operators/scan/pipeline.rs) now remove denied elements in reverse index order, so removing one element no longer shifts the elements still to be checked. Regression tests reproducing the issue were added.

The fix is included in SurrealDB 3.1.4.

Workarounds

  • Do not rely on element-level (field.*) permissions to hide data from record users; use field-level permissions, which are enforced correctly.
  • Restrict record users from selecting tables whose schema uses element-level permissions.

Resources

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iosurrealdball versions3.1.4cargo update -p surrealdb --precise 3.1.4

Affected Products

1 product · 1 configurations
Application
surrealdbsurrealdb
< 3.1.4
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for surrealdb, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update surrealdb to 3.1.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-63740 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

A `SELECT` permission defined on an array element (`DEFINE FIELD field.* … PERMISSIONS FOR select …`) is not enforced correctly for `RECORD` users. Instead of hiding the denied elements, the query leaks a subset of them: a deny-all returns the odd-indexed elements, and a per-element predicate keeps and drops the wrong ones. The filter removed each denied element by index while walking the array forwards. Because removing an element shifts every later index down, each cut invalidated the indices still pending in the loop, leaving denied elements behind. Field-level permissions are enforced cor
O3 Security · Impact-Aware SCA

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CVE-2026-63740: surrealdb — Fixed in 3.1.4