CVE-2026-57449

Actual Sync Server: CORS Proxy GitHub API Allowlist Prefix Bypass Leaks Private Repositories Through the Server GitHub Token

Published Sep 25, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed
Description
Actual is a local-first personal finance tool. Prior to 26.7.0, Actual Sync Server's CORS proxy is intended to let authenticated users fetch resources only from repositories listed in the official plugin allowlist. When `ACTUAL_GITHUB_TOKEN` is configured, the proxy automatically attaches the server's GitHub token to GitHub requests. The GitHub API allowlist check uses a raw `startsWith()` prefix test for `/repos/{owner}/{repo}` without requiring a path boundary after the repository name. If an allowlisted public plugin repository is `https://github.com/acme/plugin`, the proxy also accepts GitHub API URLs. Those URLs are outside the allowlisted repository but still pass because their API path starts with `/repos/acme/plugin`. The proxy then forwards the request with the server's `ACTUAL_GITHUB_TOKEN`, allowing any authenticated Actual user to read private GitHub resources reachable by that token. Version 26.7.0 fixes the issue.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-m62c-5q34-f3cf Actual Sync Server: CORS Proxy GitHub API Allowlist Prefix Bypass Leaks Private Repositories Through the Server GitHub Token
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Actualbudget
Actualbudget actual
Vendors & Products Actualbudget
Actualbudget actual
Type Values Removed Values Added
Description Actual is a local-first personal finance tool. Prior to 26.7.0, Actual Sync Server's CORS proxy is intended to let authenticated users fetch resources only from repositories listed in the official plugin allowlist. When `ACTUAL_GITHUB_TOKEN` is configured, the proxy automatically attaches the server's GitHub token to GitHub requests. The GitHub API allowlist check uses a raw `startsWith()` prefix test for `/repos/{owner}/{repo}` without requiring a path boundary after the repository name. If an allowlisted public plugin repository is `https://github.com/acme/plugin`, the proxy also accepts GitHub API URLs. Those URLs are outside the allowlisted repository but still pass because their API path starts with `/repos/acme/plugin`. The proxy then forwards the request with the server's `ACTUAL_GITHUB_TOKEN`, allowing any authenticated Actual user to read private GitHub resources reachable by that token. Version 26.7.0 fixes the issue.
Title Actual Sync Server: CORS Proxy GitHub API Allowlist Prefix Bypass Leaks Private Repositories Through the Server GitHub Token
Weaknesses CWE-200
CWE-284
CWE-863
References
Metrics cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 28, 2026, 1:07 PM
Reserved
Jun 24, 2026, 1:21 PM
Status
Deferred
Published
Sep 25, 2026, 11:16 PM
Modified
Sep 28, 2026, 2:17 PM