What is CVE-2026-30870?

CVE-2026-30870 is a medium-severity vulnerability in @Powersync Service-Core, classified under Improper Authorization. CVSS score: 6.5/10. Published 2026-03-10.

How severe is CVE-2026-30870?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Auth bypass in @Powersync Service-Core

CVE-2026-30870

PowerSync Service is the server-side component of the PowerSync sync engine. In version 1.20.0, when using new sync streams with config.edition: 3, certain subquery filters were ignored when determining which data to sync to users. Depending on the sync stream configuration, this could result in authenticated users syncing data that should have been restricted. Only queries that gate synchronization using subqueries without partitioning the result set are affected. This vulnerability is fixed in 1.20.1.

EPSS: 0.002 (10.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

Affected products

@Powersync Service-core — versions < 1.20.1
@Powersync Service-sync-rules — versions < 0.33.0
Powersync-ja Powersync-service — versions < 1.20.1

Weakness classification (CWE)

CWE-285 — Improper Authorization

References

security-advisories@github.com (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-30870?: CVE-2026-30870 is a medium-severity vulnerability in @Powersync Service-Core, classified under Improper Authorization. CVSS score: 6.5/10. Published 2026-03-10.
How severe is CVE-2026-30870?: Medium severity. CVSS v3 base score is 6.5 out of 10.