Flarum Framework: Use of a Key Past its Expiration Date
CVE-2026-39923 is a high-severity use of a key past its expiration date vulnerability in Flarum Framework from Flarum, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 1.8.16 as the first without the flaw, so updating Flarum Framework to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.43% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Flarum Framework to 1.8.16 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Flarum | Flarum Framework | before 1.8.16 | 1.8.16 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (vulncheck.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.2 | Critical | CNA (vulncheck.com) |
| CVSS 3.1 | 8.1 | High | CNA (vulncheck.com) |
Official description
Flarum before 1.8.16 contains a password reset token expiry bypass vulnerability that allows unauthenticated attackers to reuse expired password reset tokens by submitting them directly to the reset processing endpoint. The SavePasswordController::handle() method calls PasswordToken::findOrFail() without performing any expiry validation, allowing attackers to bypass the 24-hour token lifetime enforced only during form rendering and change any account's password to gain an authenticated session.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of a Key Past its Expiration Date
The product uses a cryptographic key past its expiration date.
How developers prevent this class of flaw
- Adequate consideration should be put into the user interface in order to notify users previous to the key's expiration, to explain the importance of new key generation and to walk users through the process as painlessly as possible.
- Replace keys within a period of time proportional to their strength.
More Use of a Key Past its Expiration Date vulnerabilities (CWE-324)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use of a Key Past its Expiration Date vulnerabilities
- 7.5 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.7 High severity
- 9.8 Critical severity
- 8.8 High severity
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