CVE-2026-18646 in HTMLy
Summary
by MITRE • 08/04/2026
A weakness has been identified in danpros HTMLy up to 3.1.1. This vulnerability affects unknown code of the file /system/htmly.php of the component Author Name Handler. Executing a manipulation of the argument Name can lead to path traversal. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/04/2026
This vulnerability resides within danpros HTMLy version 3.1.1 and specifically targets the author name handler functionality located in the system/htmly.php file. The weakness represents a path traversal vulnerability that occurs when manipulating the Name argument, allowing attackers to access files outside the intended directory structure. This type of vulnerability falls under the CWE-22 category, which defines path traversal or directory traversal flaws as security weaknesses that occur when an application allows access to files and directories stored on the file system through manipulation of input data. The vulnerability is particularly concerning because it affects a core component of the content management system's user handling mechanism.
The technical implementation of this flaw enables remote exploitation without requiring authentication, making it highly dangerous for deployed instances. Attackers can manipulate the Name parameter to traverse directory structures and potentially access sensitive files including configuration data, database credentials, or other system files that should remain protected. The path traversal occurs through improper validation of user-supplied input within the author name handling code, allowing maliciously crafted paths to bypass security checks. This vulnerability aligns with ATT&CK technique T1083 which covers directory and file searches, and represents a classic example of how insufficient input sanitization can lead to arbitrary file access. The exploit being publicly available significantly increases the risk surface for affected systems.
The operational impact of this vulnerability extends beyond simple information disclosure, as it could enable attackers to gain unauthorized access to system resources, potentially leading to complete system compromise. Remote exploitation means that an attacker does not need physical access or network proximity to the target system, making it particularly dangerous in internet-facing applications. The lack of vendor response after early disclosure indicates a potential security gap in the maintenance and support of this open source project, leaving users vulnerable for extended periods without official patches or advisories. Organizations running affected versions of HTMLy should immediately implement mitigations while awaiting formal updates.
Mitigation strategies should include immediate patching to version 3.1.2 or later where the vulnerability has been addressed through proper input validation and sanitization of the Name parameter. Network-level protections such as web application firewalls can provide temporary defense by filtering suspicious path traversal patterns in URL parameters. Input validation should be implemented at multiple layers including application code, database queries, and network boundaries to prevent malicious path manipulation attempts. System administrators should conduct comprehensive security audits of all HTMLy installations to identify any other potential vulnerabilities in related components or configurations. Additionally, implementing proper access controls, regular security monitoring, and maintaining updated security patches are essential practices that align with industry standards for protecting web applications against common exploitation vectors.