Actual Sync Server has an Authenticated Path Traversal

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-3089: 0.39% estimated exploitation activity in the next 30 days; percentile 33.43 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Description Actual Sync Server allows authenticated users to upload files through POST /sync/upload-user-file. In versions prior to 26.3.0, improper validation of the user-controlled x-actual-file-id header means that traversal segments (../) can escape the intended directory and write files outside userFiles. Mitigations The vulnerability can be mitigated in prior versions by running the sync server in a filesystem sandbox.

Published by the source

10 Mar 2026, 01:02 UTC

Last modified by the source

10 Mar 2026, 01:26 UTC

Source last checked

26 Oct 2026, 12:43 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-27vg-33gh-4hwg

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-27vg-33gh-4hwg

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# Patch Next advisory brief: CVE-2026-3089

Advisory: Actual Sync Server has an Authenticated Path Traversal
IDs: CVE-2026-3089, GHSA-27vg-33gh-4hwg
Record: https://patchnext.com/advisories/cve-2026-3089 (revision 3, source checked 26 Oct 2026, 12:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @actual-app/sync-server 26.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @actual-app/sync-server: affected <= 26.2.0; fixed in 26.3.0

## Suggested inspection (read-only)
- `npm ls @actual-app/sync-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @actual-app/sync-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-27vg-33gh-4hwg (OSV record GHSA-27vg-33gh-4hwg lists affected ranges: npm @actual-app/sync-server >=0 <26.3.0 (fixed))
- Verified: https://github.com/advisories/GHSA-27vg-33gh-4hwg (GitHub-reviewed advisory GHSA-27vg-33gh-4hwg lists affected ranges: npm @actual-app/sync-server >=0 <=26.2.0)

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