CVE-2025-27794

MEDIUM
Published Mar 12, 2025 Modified Apr 2, 2025 CWE-74

Description

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.

Is your site exposed to CVE-2025-27794?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

6.8
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

Weakness Type (CWE)

CWE-74 CWE-74

Affected Products

Vendor Product
flarum flarum

References

Frequently Asked Questions

What is CVE-2025-27794? +
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. It has a CVSS v3.1 base score of 6.8 (MEDIUM).
How severe is CVE-2025-27794? +
CVE-2025-27794 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.
What products are affected by CVE-2025-27794? +
CVE-2025-27794 affects products from flarum, specifically: flarum. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2025-27794? +
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.

Related Vulnerabilities

CVE-2026-41237

Froxlor is open source server administration software. In version 2.3.6 and earlier, the LOC record regex uses `\s+` which matches …
CVE-2024-53263

Git LFS is a Git extension for versioning large files. When Git LFS requests credentials from Git for a remote …
CVE-2025-27107

Integrated Scripting is a tool for creating scripts for handling complex operations in Integrated Dynamics. Minecraft users who use Integrated …
CVE-2025-32699

Vulnerability in Wikimedia Foundation MediaWiki, Wikimedia Foundation Parsoid.This issue affects MediaWiki: before 1.39.12, 1.42.6, 1.43.1; Parsoid: before 0.16.5, 0.19.2, 0.20.2.
CVE-2025-40710

Host Header Injection (HHI) vulnerability in the Hotspot Shield VPN client, which can induce unexpected behaviour when accessing third-party web …
CVE-2025-6785

Securing externally available CAN wires can easily allow physical access to the CAN bus, allowing possible injection of specially formed …

Don't wait for an exploit

Scan your website for vulnerabilities like CVE-2025-27794 — free, no signup required.