CVE-2026-30870
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedPowerSync 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIn PowerSync Service version 1.20.0, when using sync streams with config.edition: 3, subquery-based filters used to restrict synchronized data were incorrectly bypassed. This allowed authenticated users to sync data that should have been filtered out based on subquery conditions. The issue only affects queries that gate synchronization using subqueries without partitioning.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Identify PowerSync Service versionCheck the running PowerSync Service version using the administrative API or service metadataAffected if Version is exactly 1.20.0
-
Locate sync stream configurationFind the sync configuration file or API endpoint that defines sync streams for your applicationAffected if Configuration uses config.edition: 3 (edition value of 3) and sync streams are defined
-
Verify subquery filter usageInspect the sync stream definitions to identify if any use subquery-based filters in the WHERE clause to restrict synchronized dataAffected if Sync streams contain subquery conditions in their filter definitions without partitioning configured
-
Check partitioning statusExamine whether the affected sync streams have partitioning enabledAffected if Partitioning is NOT configured (the flaw only affects subqueries without partitioning)
-
Validate data accessReview synced data for a user who should be excluded by subquery filters - compare actual synced records against expected filtered resultsAffected if Users can sync data that should have been excluded by the subquery filter conditions
You are affected if running PowerSync Service 1.20.0 with edition: 3 sync streams using subquery-based filters without partitioning, where excluded data is incorrectly synced.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade PowerSync Service from version 1.20.0 to 1.20.1, then verify that sync stream configurations with subquery filters are correctly restricting data as intended.
1.20.1
- Upgrade PowerSync Service from version 1.20.0 to version 1.20.1
- After upgrading, verify that sync streams with config.edition: 3 correctly enforce subquery filters
- Confirm that users are only syncing data according to their intended access restrictions
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,416.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-30870 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-30870 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data