CVE-2026-43926Network attack vector

Reset-token validity disclosure via unthrottled response oracle

Published Jun 4, 2026 · Updated Jun 4, 2026

Observable response discrepancy in FOSSBilling before 0.8.0 allows remote attackers to identify valid password-reset tokens. The non-API confirmation controller bypasses the /api/* rate limiter and returns HTTP 200 for valid tokens but redirects invalid or expired tokens. Unauthenticated network access is sufficient, but successful guessing remains constrained by 256-bit tokens that expire after 15 minutes.

CVSS severity6.3
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable response discrepancy in FOSSBilling before 0.8.0 allows remote attackers to identify valid password-reset tokens. The non-API confirmation controller bypasses the /api/* rate limiter and returns HTTP 200 for valid tokens but redirects invalid or expired tokens. Unauthenticated network access is sufficient, but successful guessing remains constrained by 256-bit tokens that expire after 15 minutes.

The record

CVE
CVE-2026-43926
Published
Jun 4, 2026
Updated
Jun 4, 2026
Vendor
FOSSBilling
Product
FOSSBilling
Classifications
CWE-307, CWE-204, T1110
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FOSSBilling · FOSSBillingversion=< 0.8.0

Published CVSS scores

6.3GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
CWE-204Observable Response Discrepancy
T1110Brute Force

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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