What is the CVSS score of CVE-2025-27794?

CVE-2025-27794 has a CVSS 3.1 base score of 6.8 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N. EPSS exploitation probability: 0.2%.

Which versions of Flarum are affected by CVE-2025-27794?

Organizations using versions should be aware of notable risk from CVE-2025-27794, a injection vulnerability rated CVSS 6.8.. A patch is available.

How to fix or mitigate CVE-2025-27794?

Within 30 days: Identify affected systems running versions and apply vendor patches as part of regular patch cycle. Validate input sanitization for user-controlled parameters.

Flarum CVE-2025-27794

MEDIUM

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (CWE-74)

2025-03-12 security-advisories@github.com

Information Disclosure Flarum

6.8

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

6.8 MEDIUM

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

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

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

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:31 vuln.today

Patch released

Mar 28, 2026 - 18:31 nvd

Patch available

CVE Published

Mar 12, 2025 - 14:15 nvd

MEDIUM 6.8

DescriptionGitHub Advisory

Flarum is open-source forum software. A session hijacking vulnerability exists in versions prior to 1.8.10 when an attacker-controlled authoritative subdomain under a parent domain (e.g., subdomain.host.com) sets cookies scoped to the parent domain (.host.com). This allows session token replacement for applications hosted on sibling subdomains (e.g., community.host.com) if session tokens aren't rotated post-authentication. Key Constraints are that the attacker must control any subdomain under the parent domain (e.g., evil.host.com or x.y.host.com), and the parent domain must not be on the Public Suffix List. Due to non-existent session token rotation after authenticating we can theoretically reproduce the vulnerability by using browser dev tools, but due to the browser's security measures this does not seem to be exploitable as described. Version 1.8.10 contains a patch for the issue.

AnalysisAI

Flarum is open-source forum software. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable, no authentication required.

Technical ContextAI

This vulnerability is classified under CWE-74. Flarum is open-source forum software. A session hijacking vulnerability exists in versions prior to 1.8.10 when an attacker-controlled authoritative subdomain under a parent domain (e.g., subdomain.host.com) sets cookies scoped to the parent domain (.host.com). This allows session token replacement for applications hosted on sibling subdomains (e.g., community.host.com) if session tokens aren't rotated post-authentication. Key Constraints are that the attacker must control any subdomain under the parent domain (e.g., evil.host.com or x.y.host.com), and the parent domain must not be on the Public Suffix List. Due to non-existent session token rotation after authenticating we can theoretically reproduce the vulnerability by using browser dev tools, but due to the browser's security measures this does not seem to be exploitable as described. Version 1.8.10 contains a patch for the issue. Affected products include: Flarum. Version information: prior to 1.8.10.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.