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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2018.3314.2 Citrix XenServer Security Update 14 November 2018 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Citrix XenServer Publisher: Citrix Operating System: Virtualisation Impact/Access: Denial of Service -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2018-18883 Original Bulletin: https://support.citrix.com/article/CTX239100 Revision History: November 14 2018: Update with assigned CVE number October 29 2018: Initial Release - --------------------------BEGIN INCLUDED TEXT-------------------- CTX239100 Citrix XenServer Security Update Security Bulletin Priority: Medium Created: 26 Oct 2018 Modified: 13 Nov 2018 Applicable Products * XenServer 7.6 * XenServer 7.5 * XenServer 7.1 LTSR Cumulative Update 1 Description of Problem A security issue has been identified in Citrix XenServer that may allow a malicious administrator of an HVM guest VM to crash the host. This issue affects the following versions of Citrix XenServer: * Citrix XenServer 7.6 * Citrix XenServer 7.5 * Citrix XenServer 7.1 LTSR CU1 The following vulnerabilities have been addressed: * CVE-2018-18883: Nested VT-x usable even when disabled - ------------------------------------------------------------------------------- Mitigating Factors Customers with only PV guests are not affected by this issue. - ------------------------------------------------------------------------------- What Customers Should Do Hotfixes have been released to address this issue. Citrix recommends that affected customers install these hotfixes as their patching schedule permits. The hotfixes can be downloaded from the following locations: Citrix XenServer 7.6: CTX239128 - https://support.citrix.com/article/CTX239128 Citrix XenServer 7.5: CTX239127 - https://support.citrix.com/article/CTX239127 Citrix XenServer 7.1 LTSR CU1: CTX239126 - https://support.citrix.com/article/ CTX239126 Customers who are using the LivePatching feature of Citrix XenServer will not need to reboot servers to apply this hotfix if those servers were previously fully patched. - ------------------------------------------------------------------------------- Changelog +-----------------------------------------------------------------------------+ |Date |Change | |--------------------------------------+--------------------------------------| |26th October 2018 |Initial Issue | |--------------------------------------+--------------------------------------| |1st November 2018 |Update with assigned CVE number | +-----------------------------------------------------------------------------+ - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBW+u0JGaOgq3Tt24GAQiOIg//VYERkGKwnQFknhkaCYkavKcof4qH5Bvl 67Al/f7HqADZ6HCsNtZFAWsjEB7OtxT6aUVTIhWq8uJKgnCO0f897JpbVAwGzpD/ vm8sq35xhoegeP4UEHQqC8D2ES4XAxsgfwxbPtcFSg8meS49RHZzHqPhzIGPjLiM YjRBH1du4UaBsNChvCa5v4w08c5fu/rCNQ5SZ72ulYwjujSInUaSQ/4cY7wjtACd tO2hhjvPFuJ8VewZDbX0+C5fO+dTTs3rsdDhNst0AszXWSmkr7KYO+weUrazHKYX dw8xJwMrQyuuL/MgqhUVArqFODQ77CoUm+T130FBctnU+usL3nzfKEVGLznPEqm5 w6ubn0miW9L4HMSwa9TW/J399Q9i2JQ72tOE74PYH9ryylYkE0ejbgfuTwa67wAK VpxFxuzsYvyDxaIYhN0hNyUEQZPxLu0T7cTH4kdleDlwHMQTBk+50fDTxfzUnDg7 cydYs3QUL7e4op967U4a4bt9OiVWTGzPWUxNUU0q0D2/BnrRnsZeZa8vTYUc9kxP h+DqVXMFQORaoEbrfu5CMb0giMFKhmPnN35okzspgJ5US3sqjG+mYzCVYBQhmU3j inTnaWAnJGgdEDID8A1S7JWUTIBZUiadcFaXpr6SL5/Ie8qzPBhlz6YnzhMZz27U Btm66WkqNgk= =5RyH -----END PGP SIGNATURE-----