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CWE-640Weakness · CWE-640

CVE-2026-53646

HIGH · 7.7 CVSS v4.0 Published 2026-07-06
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 7 weeks old

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
FOSSBilling is a free, open-source billing and client management system. In versions 0.5.6 through 0.7.2, when a `ClientPasswordReset` record already exists for a client (from a previous unexpired reset request), subsequent calls to the `reset_password` guest API endpoint reuse the existing token instead of generating a new one. The 15-minute validity window is anchored to the first request's `created_at` timestamp, not the time of the most recent email. An attacker who obtained the original reset link remains able to use it even after the victim requests a new reset, because the original token is never invalidated or rotated. Version 0.8.0 patches the issue. Some workarounds are available. Configure a reverse proxy (e.g., Nginx, Apache, Cloudflare) to apply per-IP rate limiting to the `/client/reset-password` endpoint to minimize the window of opportunity, and/or manually clear expired `client_password_reset` records from the database after a client reports a suspected compromise.

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

In FOSSBilling versions 0.5.6-0.7.2, the reset_password guest API endpoint does not invalidate existing password reset tokens when a client requests a new reset. Instead, it reuses the original token and preserves the original created_at timestamp, allowing the original 15-minute validity window to persist. An attacker who obtained a reset link before the victim requested a new reset can still use that link within the original window.

MitigationUpgrade to FOSSBilling version 0.8.0 or apply rate limiting to the /client/reset-password endpoint as a temporary workaround until the patch can be deployed.

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
High
Privileges
None
Authentication
X
User interaction
P
Scope
X

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/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 installed FOSSBilling version
    Check the version file (typically version.php or similar in the installation root), or log into the admin dashboard and navigate to Settings > About or System > Information to view the installed version
    Affected if The installed version falls within 0.5.6 to 0.7.2 (inclusive)
  2. Confirm guest API reset_password endpoint is accessible
    Verify the /api/guest/client/reset-password endpoint is reachable. This is typically a guest-public API endpoint. Check your web server access logs or API documentation for endpoint availability
    Affected if The guest reset_password API endpoint is enabled and accessible without authentication
  3. Verify token handling behavior (code inspection)
    Examine the source code in the reset password handler (typically in src/Api/Internal.php or similar guest API handlers). Look for the reset_password function and check if it creates a new token or reuses the existing one when a new reset is requested
    Affected if The code shows that when a new reset request is made, it reuses the existing token instead of generating a new one with a fresh timestamp

You are affected if FOSSBilling version 0.5.6-0.7.2 is installed AND the guest API reset_password endpoint is accessible, as the token reuse vulnerability allows old reset links to remain valid beyond their intended window.

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 FOSSBilling version 0.8.0 or apply rate limiting to the /client/reset-password endpoint as a temporary workaround until the patch can be deployed.

Recommended fix High confidence

FOSSBilling version 0.8.0 or later

  1. 1. Upgrade FOSSBilling from version 0.5.6-0.7.2 to version 0.8.0 or later to receive the security patch
  2. 2. Verify the upgrade was successful by checking the FOSSBilling version in the admin panel
  3. 3. As an additional precaution, configure a reverse proxy (Nginx, Apache, or Cloudflare) to apply per-IP rate limiting to the `/client/reset-password` endpoint
  4. 4. Manually clear any expired `client_password_reset` records from the database after upgrading

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

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,220
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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-2026-53646 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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