CVE-2025-66578

MEDIUM
Published Dec 9, 2025 Modified Dec 11, 2025 CWE-248

Description

xmlseclibs is a library written in PHP for working with XML Encryption and Signatures. Versions 3.1.3 contain an authentication bypass vulnerability due to a flaw in the libxml2 canonicalization process during document transformation. When libxml2’s canonicalization is invoked on an invalid XML input, it may return an empty string rather than a canonicalized node. xmlseclibs then proceeds to compute the DigestValue over this empty string, treating it as if canonicalization succeeded. This issue is fixed in version 3.1.4. Workarounds include treating canonicalization failures (exceptions or nil/empty outputs) as fatal and aborting validation, and/or adding explicit checks to reject when canonicalize returns nil/empty or raises errors.

Is your site exposed to CVE-2025-66578?

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

CVSS v3.1 Score

6.0
MEDIUM
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:L/A:L

Weakness Type (CWE)

CWE-248 CWE-248

Affected Products

Vendor Product
xmlseclibs_project xmlseclibs

References

Frequently Asked Questions

What is CVE-2025-66578? +
xmlseclibs is a library written in PHP for working with XML Encryption and Signatures. Versions 3.1.3 contain an authentication bypass vulnerability due to a flaw in the libxml2 canonicalization process during document transformation. When libxml2’s canonicalization is invoked on an invalid XML input, it may return an empty string rather than a canonicalized node. xmlseclibs then proceeds to compute the DigestValue over this empty string, treating it as if canonicalization succeeded. This issue is fixed in version 3.1.4. Workarounds include treating canonicalization failures (exceptions or nil/empty outputs) as fatal and aborting validation, and/or adding explicit checks to reject when canonicalize returns nil/empty or raises errors. It has a CVSS v3.1 base score of 6.0 (MEDIUM).
How severe is CVE-2025-66578? +
CVE-2025-66578 has a CVSS v3.1 score of 6.0 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-2025-66578? +
CVE-2025-66578 affects products from xmlseclibs_project, specifically: xmlseclibs. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2025-66578? +
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-2025-24883

go-ethereum (geth) is a golang execution layer implementation of the Ethereum protocol. A vulnerable node can be forced to shutdown/crash …
CVE-2025-43855

tRPC allows users to build & consume fully typesafe APIs without schemas or code generation. In versions starting from 11.0.0 …
CVE-2025-48997

Multer is a node.js middleware for handling `multipart/form-data`. A vulnerability that is present starting in version 1.4.4-lts.1 and prior to …
CVE-2025-53365

The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to …
CVE-2025-53366

The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to …
CVE-2025-53620

@builder.io/qwik-city is the meta-framework for Qwik. When a Qwik Server Action QRL is executed it dynamically load the file containing …

Don't wait for an exploit

Scan your website for vulnerabilities like CVE-2025-66578 — free, no signup required.