dbcve.org
Incorrect AuthorizationWeakness · CWE-863

CVE-2026-42604

MEDIUM · 6.9 CVSS v4.0 Published 2026-06-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Actual is a local-first personal finance tool. The `POST /openid/config` endpoint in Actual Budget's sync-server versions <= 26.4.0 exposes the full OpenID Connect configuration—including the OAuth2 `client_secret`—to any caller who knows the bootstrap password. The endpoint also lacks authentication and rate limiting, making the bootstrap password brute-forceable. Version 26.5.0 fixes the issue.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The POST /openid/config endpoint in Actual Budget's sync-server versions <=26.4.0 exposes the full OpenID Connect configuration including the OAuth2 client_secret to any caller who knows the bootstrap password. The endpoint lacks both authentication and rate limiting, enabling brute-force attacks against the bootstrap password.

MitigationUpgrade to version 26.5.0 or later which contains the fix. Additionally, implement rate limiting on the endpoint and enforce strong bootstrap passwords to mitigate brute-force risk.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the sync-server installation and version
    Locate the Actual Budget sync-server instance and determine its installed version number. This is typically found in the application metadata, package.json, docker image tag, or running service version info.
    Affected if The installed version is 26.4.0 or any earlier version (versions <=26.4.0 are affected)
  2. Verify the /openid/config endpoint is exposed
    Send a POST request to http(s)://<server>/openid/config (or the equivalent path on your sync-server instance). No authentication headers or credentials should be required to reach the endpoint.
    Affected if The endpoint responds without requiring any authentication or credentials
  3. Confirm the endpoint returns sensitive configuration
    Examine the response from the POST /openid/config endpoint. Look for fields including client_secret, client_id, and other OAuth2/OpenID Connect configuration parameters.
    Affected if The response contains OAuth2 client_secret or other OpenID Connect configuration details in plain text
  4. Check for rate limiting on the endpoint
    Inspect the server configuration, reverse proxy settings, or application-level rate limiting rules to determine if the /openid/config endpoint has any rate limiting or request throttling configured.
    Affected if No rate limiting is configured and the endpoint is accessible without throttling protections

A user is affected if they are running Actual Budget sync-server version 26.4.0 or earlier AND the /openid/config endpoint responds without authentication and exposes OAuth2 client_secret in the response.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to version 26.5.0 or later which contains the fix. Additionally, implement rate limiting on the endpoint and enforce strong bootstrap passwords to mitigate brute-force risk.

Recommended fix High confidence

26.5.0

  1. 1. Backup your current Actual Budget instance and configuration data before upgrading
  2. 2. Locate your Actual Budget sync-server deployment (Docker container, npm installation, or other)
  3. 3. Stop the running sync-server instance
  4. 4. Update Actual Budget to version 26.5.0 or later using your deployment method (e.g., pull new Docker image, run npm update, or use your package manager)
  5. 5. Verify the `/openid/config` endpoint no longer exposes client_secret without proper authentication
  6. 6. Restart the sync-server service
  7. 7. Test that OpenID authentication continues to work correctly after the upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42604 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data