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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.003 (25.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
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)
References
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.