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CVE-2026-53646

FOSSBilling: Client password reset token reuse allows persistent account takeover

7.7 High

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
Passive

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.31%Up 0.3 points since Jun 12, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.7

FOSSBilling: Client password reset token reuse allows persistent account takeover

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.

Record
CVE-2026-53646
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-640
Updated
2026-11-02
EUVDEUVD-2026-41971 7.7

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.

Record
EUVD-2026-41971
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
NVD 7.7

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.

Record
CVE-2026-53646
CVSS 4.0
7.7 HighCVSS: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
Weakness
CWE-640
Updated
2026-11-02
OSV 7.7

FOSSBilling: Client password reset token reuse allows persistent account takeover

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.

Record
CVE-2026-53646
CVSS 4.0
7.7 HighCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-640
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-53646 is a high vulnerability (CVSS 7.7) in Fossbilling, published July 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 24th percentile. No source names a fixed version.

References

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