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Category:   Application (Generic)  >   Shibboleth Service Provider Vendors:   Shibboleth
Shibboleth Service Provider Flaw Lets Remote Users Modify User Data on the Target System
SecurityTracker Alert ID:  1040435
SecurityTracker URL:
CVE Reference:   CVE-2018-0489   (Links to External Site)
Date:  Feb 27 2018
Impact:   Disclosure of user information, Modification of user information
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   A vulnerability was reported in Shibboleth Service Provider. A remote user can modify data on the target system.

A remote user can add or modify certain XML constructs to trigger a flaw in the XMLTooling library and bypass digital signature verification. This can be exploited to modify user data and impersonate a user or obtain potentially sensitive information.

Kelby Ludwig, Duo Security, and Scott Cantor, Shibboleth Project, reported this vulnerability.

Impact:   A remote user can bypass digital signature verification to impersonate a user or obtain potentially sensitive information.
Solution:   The vendor has issued a fix (; or upgrade XMLTooling-C library to version 1.6.4).

The vendor advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Authentication error

Message History:   None.

 Source Message Contents

Subject:  Shibboleth Service Provider Security Advisory [27 February 2018]

Hash: SHA256

Shibboleth Service Provider Security Advisory [27 February 2018]

An updated version of the Shibboleth Project's XMLTooling library is
available which corrects a critical security issue.

Shibboleth SP software vulnerable to additional data forgery flaws
The XML processing performed by the Service Provider software has been
found to be vulnerable to new flaws similar in nature to the one
addressed in an advisory last month [1].

These bugs involve the use of other XML constructs rather than entity
references, and therefore required additional mitigation once discovered.
As with the previous issue, this flaw allows for changes to an XML document
that do not break a digital signature but can alter the user data passed
through to applications behind the SP and result in impersonation attacks
and exposure of protected information.

As before, the use of XML Encryption is a significant mitigation, but we
have not dismissed the possibility that attacks on the Response "envelope"
may be possible, in both the original and this new case. No actual attacks
of this nature are known, so deployers should prioritize patching systems
that expect to handle unencrypted SAML assertions.

An updated version of XMLTooling-C (V1.6.4) is available [2] that protects
against these new attacks, and should help prevent similar vulnerabilities
in the future.

Unlike the previous case, these bugs are NOT prevented by any existing
Xerces-C parser version on any platform and cannot be addressed by any
means other than the updated XMLTooling-C library.

ALL supported (and unsupported) platforms are impacted by these bugs,
including Windows, Linux, Solaris, and OS X.

This vulnerability has been assigned CVE-2018-0489 and is referenced by
a CERT Vulnerability Note at [3].

Upgrade to V1.6.4 or later of the XMLTooling-C library and restart the
affected processes (shibd, Apache, etc.)

Linux installations relying on official RPM packages can upgrade to
the latest package versions to obtain the fix.

The MacPort has also been updated.

Windows systems can upgrade to the latest Service Provider release
(V2.6.1.4) which contains the appropriately updated libraries. [4]

Kelby Ludwig, Duo Security
Scott Cantor, Shibboleth Project


URL for this Security Advisory:

Version: GnuPG v2


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