PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-42604 actualbudget CVE debrief

A vulnerability was discovered in Actual Budget's sync-server versions <= 26.4.0. The `POST /openid/config` endpoint exposes the full OpenID Connect configuration, including the OAuth2 `client_secret`, to any caller who knows the bootstrap password. The endpoint lacks authentication and rate limiting, making the bootstrap password brute-forceable. This issue was fixed in version 26.5.0.

Vendor
actualbudget
Product
actual
CVSS
MEDIUM 6.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-12
Original CVE updated
2026-06-16
Advisory published
2026-06-12
Advisory updated
2026-06-16

Who should care

Users of Actual Budget's sync-server versions <= 26.4.0 should be aware of this vulnerability and take action to protect their systems.

Technical summary

The `POST /openid/config` endpoint in Actual Budget's sync-server versions <= 26.4.0 exposes sensitive information, including the OAuth2 `client_secret`. This endpoint lacks authentication and rate limiting, making it vulnerable to brute-force attacks.

Defensive priority

MEDIUM

Recommended defensive actions

  • Upgrade to version 26.5.0 or later
  • Review and secure the bootstrap password
  • Monitor for suspicious activity on the sync-server

Evidence notes

The CVE-2026-42604 record was obtained from the official CVE.org database.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-42604 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-42604

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-42604 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-42604

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.