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CVE-2025-66578

25
FAUCET Score

CVE-2025-66578 is an authentication bypass vulnerability in xmlseclibs versions 3.1.3 and earlier, a PHP library for XML Encryption and Signatures. The flaw stems from libxml2's canonicalization process, which can return an empty string for invalid XML, leading xmlseclibs to incorrectly compute a DigestValue and bypass authentication. Rated 7.5 HIGH (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N), this vulnerability is remotely exploitable with low attack complexity, allowing for high integrity impact without user interaction. There is currently no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.1.4CPE matchmatch criteria
cpe:2.3:a:xmlseclibs_project:xmlseclibs:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.0MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
1.2
Impact Score
4.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.23%
Probability of exploitation in next 30 days
EPSS Percentile
13.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0023 is in the 1st percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

composerpatch availablevia ghsa
Product: robrichards/xmlseclibsFixed in: 3.1.4
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-c4cc-x928-vjw9medium

robrichards/xmlseclibs has an Libxml2 Canonicalization error which can bypass Digest/Signature validation

Dec 8, 2025

References

github.com / robrichards/xmlseclibs/blob/f4131320c6dcd460f1b0c67f16f8bf24ce4b5c3e/src/XMLSecurityDSig.php
Product
github.com / robrichards/xmlseclibs/commit/69fd63080bc47a8d51bc101c30b7cb756862d1d6
Patch
github.com / robrichards/xmlseclibs/security/advisories/GHSA-c4cc-x928-vjw9
ExploitVendor Advisory