CVE-2024-21641VulnerabilityPublished 5 Jan 2024Updated 3 Jun 2025

CVE-2024-21641: flarum framework · Open Redirect

Affects flarum frameworkSource CVE Database V5

Not known to be exploited · public detection template (Nuclei) · CVSS 6.5 Medium : upgrade to 1.8.5 when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 1.0% chance of exploitation in 30 days – higher than 64% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.8.5

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 Jan 2024
Detectable: evidence found.
nuclei template: Flarum < 1.8.5 - Open Redirect
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade flarum/framework to 1.8.5.

Affected software

Product	Affected	Fixed in
GitHubflarum/framework`pkg:github/flarum/framework`Other threats	Affected <1.8.5	Fixed in 1.8.5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should promptly upgrade all Flarum installations to version 1.8.5 or later to apply the official patch that removes the unsafe redirect parameter behavior. Until upgrading is possible, administrators should audit and, if necessary, disable or carefully review any third-party extensions that modify the logout route to ensure they do not introduce similar open redirect risks. Implementing strict validation or whitelisting of redirect URLs can prevent arbitrary redirection. Additionally, organizations should educate users about the risks of unexpected redirects and encourage vigilance against phishing attempts. Web application firewalls (WAFs) can be configured to detect and block suspicious redirect parameters targeting the logout route. Monitoring logs for unusual redirect patterns can help detect exploitation attempts early. Finally, organizations should review their incident response plans to address potential phishing campaigns leveraging this vulnerability.

Description

Flarum is open source discussion platform software. Prior to version 1.8.5, the Flarum `/logout` route includes a redirect parameter that allows any third party to redirect users from a (trusted) domain of the Flarum installation to redirect to any link. For logged-in users, the logout must be confirmed. Guests are immediately redirected. This could be used by spammers to redirect to a web address using a trusted domain of a running Flarum installation. The vulnerability has been fixed and published as flarum/core v1.8.5. As a workaround, some extensions modifying the logout route can remedy this issue if their implementation is safe.

Impact

For European organizations using Flarum as a discussion or community platform, this vulnerability could lead to reputational damage and user trust erosion if attackers exploit the open redirect to conduct phishing or malware distribution campaigns. Users redirected from a trusted domain may be more likely to fall victim to social engineering attacks. While the vulnerability does not allow direct data theft or system compromise, the indirect impact on user security and organizational credibility can be significant, especially for sectors handling sensitive discussions or customer interactions. Additionally, regulatory compliance under GDPR may be implicated if user data or trust is compromised through phishing attacks facilitated by this vulnerability. The impact is more pronounced for organizations with large user bases or those in regulated industries where user trust and data protection are critical.

Summary

CVE-2024-21641 is a medium-severity security vulnerability classified as CWE-601 (URL Redirection to Untrusted Site, commonly known as an 'Open Redirect') affecting the Flarum open-source discussion platform framework versions prior to 1.8.5. The vulnerability resides in the /logout route of Flarum, which accepts a redirect parameter. This parameter can be manipulated by an attacker to redirect users from a trusted Flarum domain to any arbitrary external URL. For logged-in users, logout requires confirmation before redirection, but guests are redirected immediately without confirmation. This behavior can be exploited by attackers, such as spammers or phishers, to leverage the trusted domain of a legitimate Flarum installation to redirect users to malicious websites. This can facilitate phishing attacks, social engineering, or distribution of malware by exploiting the trust users place in the original domain. The vulnerability does not directly compromise confidentiality or availability but impacts integrity by enabling attackers to manipulate user navigation flow. The issue has been fixed in Flarum core version 1.8.5. No known exploits are currently reported in the wild. Some third-party extensions that modify the logout route may mitigate the issue if implemented securely. The CVSS v3.1 base score is 6.5 (medium), reflecting network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, no confidentiality impact, high integrity impact, and no availability impact.

CWE-601URL Redirection to Untrusted Site ('Open Redirect') (opens in a new tab)
Base weaknessLikelihood of exploit: LowOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design
Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
Architecture and Design · Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
OWASP Cheat Sheets
Mass Assignment (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V5.1.5 (opens in a new tab)
Attack patterns
Cross-Site Flashing (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Jul 2025, 23:56 UTC

Public exploits and detectiona Nuclei detection template

WeaknessesCWE-601

Technical details

References

Community reviews

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