CVE-2026-27638 ActualBudget missing authorization in sync endpoints allows cross-user budget file access in multi-user mode
In multi-user mode, authenticated users can access and modify other users' budget files due to missing ownership checks on sync endpoints.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27638?
CVE-2026-27638 is a medium-severity missing authorization vulnerability in actualbudget actual, published on 26 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Actual is a local-first personal finance tool. Prior to version 26.2.1, in multi-user mode (OpenID), the sync API endpoints (`/sync/*`) don't verify that the authenticated user owns or has access to the file being operated on. Any authenticated user can read, modify, and overwrite any other user's budget files by providing their file ID. Version 26.2.1 patches the issue.
Weakness: CWE-862
Which versions are affected by CVE-2026-27638?
2 open source packages ship an affected version, including @actual-app/sync-server. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@actual-app/sync-server npm | All versions | 26.2.1 |
@actual-app/sync-server npm | All versions | 26.2.1 |
Products include Actualbudget Actual.
How do I fix CVE-2026-27638?
Upgrade @actual-app/sync-server to 26.2.1 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-27638 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27638 exists.
Other vulnerabilities in actualbudget actual
Sources
Also known as GHSA-qmjj-p7m9-wjrv.