haxtheweb haxcms-nodejs up to 25.x PHP Backend hmacBase64 key information disclosure

Summaryinfo

A vulnerability categorized as problematic has been discovered in haxtheweb haxcms-nodejs up to 25.x. Impacted is the function hmacBase64 of the component PHP Backend. Such manipulation of the argument key leads to information disclosure. This vulnerability is listed as CVE-2026-46395. The attack may be performed from remote. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in haxtheweb haxcms-nodejs up to 25.x and classified as problematic. Affected by this issue is the function hmacBase64 of the component PHP Backend. The manipulation of the argument key with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. CVE summarizes:

HAX CMS helps manage microsite universe with PHP or NodeJs backends. Prior to version 26.0.0, the `hmacBase64()` function in the HAXcms Node.js backend contains two critical cryptographic implementation errors that together allow any unauthenticated attacker to extract the system’s private signing key and forge arbitrary admin-level JSON Web Tokens (JWTs) allowing them to get full admin access with a single HTTP request. First, the function passes the literal string "0" as the HMAC signing key instead of the key parameter, making every HAXcms instance compute identical HMACs for the same input. Then, after computing the HMAC, the function concatenates the real key parameter which is "this.privateKey + this.salt", the system’s master signing secret is directly onto the output. The combined buffer is base64-encoded and returned as the token. Every base64url token produced has the same structure: 32 bytes HMAC keyed with "0" and N bytes of `privateKey+salt`. An attacker base64-decodes any token, discards the first 32 bytes, and reads the private key directly. The `/system/api/connectionSettings` endpoint is unauthenticated and returns multiple tokens generated by this function. A single GET request to this endpoint exposes the private key. The PHP backend implements this function correctly with the actual key and returns only the hash. The PHP version produces 44-character tokens whereas the broken Node.js version produces 139+ character tokens. Version 26.0.0 fixes the issue.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-46395 since 05/13/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1592 by the MITRE ATT&CK project.

Upgrading to version 26.0.0 eliminates this vulnerability.

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Productinfo

Vendor

• haxtheweb

Name

• haxcms-nodejs

Version

• 25.x

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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