CVE-2026-39924
Flarum < 1.8.16 Session Persistence via Improper Access Token Revocation
Description
Flarum before 1.8.16 contains an improper session invalidation vulnerability that allows attackers who hold a valid session token to retain full account access after a victim changes their password, because the access_tokens table is never cleared on password change events. The TokensClearer::clearPasswordTokens() function only removes rows from the password_tokens table while leaving all active session cookies and API bearer tokens intact, including long-lived RememberAccessToken entries, and administrator-forced password resets via the user update endpoint are equally ineffective at revoking attacker-held sessions.
INFO
Published Date :
Aug. 5, 2026, 4:16 p.m.
Last Modified :
Oct. 23, 2026, 9:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 4.0 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update Flarum to version 1.8.16 or newer.
- Ensure session tokens are properly invalidated on password changes.
- Clear the access_tokens table on password reset events.
- Review session management for security.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39924.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39924 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39924
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-39924 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39924 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Oct. 23, 2026
Action Type Old Value New Value Added Translation Title: Flarum Framework de Flarum, Description: Flarum antes de 1.8.16 contiene una vulnerabilidad de invalidación de sesión impropia que permite a los atacantes que poseen un token de sesión válido retener acceso completo a la cuenta después de que una víctima cambia su contraseña, porque la tabla access_tokens nunca se borra en los eventos de cambio de contraseña. La función TokensClearer::clearPasswordTokens() solo elimina filas de la tabla password_tokens mientras deja intactas todas las cookies de sesión activas y los tokens portadores de API, incluidas las entradas RememberAccessToken de larga duración, y los restablecimientos de contraseña forzados por el administrador a través del endpoint de actualización de usuario son igualmente ineficaces para revocar las sesiones en poder del atacante. -
New CVE Received by [email protected]
Aug. 05, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/flarum/framework', 'vendor': 'Flarum', 'product': 'Flarum Framework', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '1.8.16', 'versionType': 'semver'}], 'packageURL': 'pkg:github/flarum/framework', 'defaultStatus': 'affected'}] Added Description Flarum before 1.8.16 contains an improper session invalidation vulnerability that allows attackers who hold a valid session token to retain full account access after a victim changes their password, because the access_tokens table is never cleared on password change events. The TokensClearer::clearPasswordTokens() function only removes rows from the password_tokens table while leaving all active session cookies and API bearer tokens intact, including long-lived RememberAccessToken entries, and administrator-forced password resets via the user update endpoint are equally ineffective at revoking attacker-held sessions. Added CVSS V4.0 AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/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 Added CVSS V3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N Added CWE CWE-613 Added Reference https://github.com/flarum/framework/commit/5f080293a029d0d273eb9678d597c74ea86a3bcc Added Reference https://github.com/flarum/framework/pull/4546 Added Reference https://github.com/flarum/framework/releases/tag/v1.8.16 Added Reference https://www.vulncheck.com/advisories/flarum-session-persistence-via-improper-access-token-revocation -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 05, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-39924', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-05T15:48:45.636552Z'}