CVE-2025-66578Network attack vector

Authentication bypass via failed canonicalization digest

Published Dec 9, 2025 · Updated Dec 9, 2025

Authentication bypass in Rob Richards xmlseclibs before 3.1.4 allows attackers to replay signed XML messages over a network. XMLSecurityDSig::canonicalizeData passes libxml2's failed canonicalization result to digest calculation instead of treating the failure as fatal. Exploitation requires a previously valid signature over the failed canonical form, enabling replay and authentication as the signed identity.

CVSS severity6.0
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Rob Richards xmlseclibs before 3.1.4 allows attackers to replay signed XML messages over a network. XMLSecurityDSig::canonicalizeData passes libxml2's failed canonicalization result to digest calculation instead of treating the failure as fatal. Exploitation requires a previously valid signature over the failed canonical form, enabling replay and authentication as the signed identity.

The record

CVE
CVE-2025-66578
Published
Dec 9, 2025
Updated
Dec 9, 2025
Vendor
Rob Richards
Product
xmlseclibs
Classifications
CWE-248
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 9, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.1.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Rob Richards · xmlseclibsversion=< 3.1.4

Published CVSS scores

6.0GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:L/A:L
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-248Uncaught Exception

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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