# CVE-2026-3089: Actual Sync Server 26.2.1 - Authenticated Path Traversal

> Authenticated attackers can exploit path traversal in the file upload endpoint to write files outside the intended directory.

- **Severity:** Medium 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Mar 2026
- **Updated:** 9 Mar 2026
- **Also known as:** GHSA-27vg-33gh-4hwg

## What is CVE-2026-3089?

CVE-2026-3089 is a medium-severity path traversal vulnerability in Actual Sync Server, published on 9 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.This issue affects prior versions of Actual Sync Server 26.3.0.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-3089?

2 open source packages ship an affected version, including @actual-app/sync-server. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@actual-app/sync-server` | npm | All versions | 26.3.0 |
| `@actual-app/sync-server` | npm | All versions | 26.3.0 |

Products: Actualbudget Actual.

## How do I fix CVE-2026-3089?

Upgrade @actual-app/sync-server to 26.3.0 or later.

## Is CVE-2026-3089 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3089 exists.

## Other vulnerabilities in Actual Sync Server

- [CVE-2026-27584](https://insights.sbomify.com/CVE-2026-27584/): ActualBudget server is Missing Authentication for SimpleFIN and Pluggy AI bank sync endpoints (critical 9.2)
- [CVE-2026-33318](https://insights.sbomify.com/CVE-2026-33318/): Actual has Privilege Escalation via 'change-password' Endpoint on OpenID-Migrated Servers (high 8.8)
- [CVE-2026-27638](https://insights.sbomify.com/CVE-2026-27638/): ActualBudget missing authorization in sync endpoints allows cross-user budget file access in multi-user mode (medium 5.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3089 and fix it if it is affected.

What it is: CVE-2026-3089 is a medium-severity path traversal vulnerability in Actual Sync Server, published on 9 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3089 exists.

Affected packages and fixed versions:
- @actual-app/sync-server (npm): affected all versions; fixed in 26.3.0
- @actual-app/sync-server (npm): affected all versions; fixed in 26.3.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-3089/ (Markdown: https://insights.sbomify.com/CVE-2026-3089/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3089
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3089
- OSV: https://osv.dev/vulnerability/CVE-2026-3089

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3089/
Summaries are generated and may contain mistakes; the official description above is the record.