Details
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Software: Relevanssi Premium
Version: v1.14.4
Homepage: https://www.relevanssi.com/
Advisory report: https://security.dxw.com/advisories/unserialization-vulnerability-in-relevanssi-premium-could-allow-admins-to-execute-arbitrary-code-in-some-circumstances/
CVE: Awaiting assignment
CVSS: 9 (High; AV:N/AC:L/Au:S/C:C/I:C/A:C)

Description
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Unserialization vulnerability in Relevanssi Premium could allow admins to execute arbitrary code (in some circumstances)

Vulnerability
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If logged in as an admin on any site you can go to settings, Relevanssi Premium, import or export options. This is a text field that accepts a serialised PHPA object. It is possible to submit a string that contains an evil encoded object that executes arbitrary code (if there are classes available with particular methods such as __destruct).




Proof of concept
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AchievingA arbitrary code executionA depends onA which classes are available (i.e. which plugins and themes are installed and active). It wonat be possible in all situations.

Mitigations
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Upgrade to versionA 1.14.6.1 or later.

Disclosure policy
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dxw believes in responsible disclosure. Your attention is drawn to our disclosure policy: https://security.dxw.com/disclosure/

Please contact us on security@dxw.com to acknowledge this report if you received it via a third party (for example, plugins@wordpress.org) as they generally cannot communicate with us on your behalf.

This vulnerability will be published if we do not receive a response to this report with 14 days.

Timeline
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2016-10-07: Discovered
2016-11-01: Reported
2016-11-02:A Vendor reported fixed
2016-11-17: Requested CVE
2016-11-17:A Advisory published



Discovered by dxw:
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Glyn Wintle
Please visit security.dxw.com for more information.