Summary
Actual Sync Server has an Authenticated Path Traversal
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.
Impact
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-3089? CVE-2026-3089 is a medium-severity path traversal vulnerability in @actual-app/sync-server (npm), affecting versions <= 26.2.0. It is fixed in 26.3.0. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- Which versions of @actual-app/sync-server are affected by CVE-2026-3089? @actual-app/sync-server (npm) versions <= 26.2.0 is affected.
- Is there a fix for CVE-2026-3089? Yes. CVE-2026-3089 is fixed in 26.3.0. Upgrade to this version or later.
- Is CVE-2026-3089 exploitable, and should I be worried? Whether CVE-2026-3089 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-3089 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-3089? Upgrade
@actual-app/sync-serverto 26.3.0 or later.