CVE-2026-39923Network attack vector

Account takeover via unchecked expired reset tokens

Published Aug 5, 2026 · Updated Aug 5, 2026

Password-reset expiry bypass in Flarum before 1.8.16 allows remote attackers with stale tokens to take over affected accounts. SavePasswordController::handle() passes the supplied passwordToken to PasswordToken::findOrFail(), which checks only database presence and omits the 24-hour expiry enforced by GET /reset/{token}. Possession of an expired token from a leaked email or database backup is required; POST /reset then changes the account password and issues an authenticated session.

CVSS severity9.2
Critical
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Password-reset expiry bypass in Flarum before 1.8.16 allows remote attackers with stale tokens to take over affected accounts. SavePasswordController::handle() passes the supplied passwordToken to PasswordToken::findOrFail(), which checks only database presence and omits the 24-hour expiry enforced by GET /reset/{token}. Possession of an expired token from a leaked email or database backup is required; POST /reset then changes the account password and issues an authenticated session.

The record

CVE
CVE-2026-39923
Published
Aug 5, 2026
Updated
Aug 5, 2026
Vendor
Flarum
Product
Flarum
Classifications
CWE-324, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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 <1.8.16

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Flarum · Flarumversion=0 <1.8.16

Published CVSS scores

8.1VulnCheckCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
9.2VulnCheckCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/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-324Use of a Key Past its Expiration Date
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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