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Fencer Intel
high 7.7

CVE-2026-53646 json

FOSSBilling: Client password reset token reuse allows persistent account takeover

published 4mo ago modified 4mo ago also EUVD-2026-41971

cvss
7.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 24%
public exploits
0
none known

Summary

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.

Patch / fix

  • fossbilling fossbilling 0.8.0

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
4mo ago

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 7.7 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
CNA 4.0 7.7 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

Affected products

  • FOSSBilling FOSSBilling

Classification

Weakness
  • CWE-640 Weak Password Recovery Mechanism for Forgotten Password

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.