CVE-2026-39924 (CVSS 6.8)

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.

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CVSS v3.1 Score

6.8

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Weakness Type (CWE)

CWE-613 CWE-613

References

Other References

https://github.com/flarum/framework/commit/5f080293a029d0d273eb9678d597c74ea86a3bcc https://github.com/flarum/framework/pull/4546 https://github.com/flarum/framework/releases/tag/v1.8.16 https://www.vulncheck.com/advisories/flarum-session-persistence-via-improper-access-token-revocation

Frequently Asked Questions

What is CVE-2026-39924? +

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. It has a CVSS v3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2026-39924? +

CVE-2026-39924 has a CVSS v3.1 score of 6.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-39924? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-39924