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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2018.3438 CTX239100: Citrix XenServer Security Update 2 November 2018 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Citrix XenServer Publisher: Citrix Operating System: Xen Impact/Access: Denial of Service -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2018-18883 Original Bulletin: https://support.citrix.com/article/CTX239100 - --------------------------BEGIN INCLUDED TEXT-------------------- CTX239100 Citrix XenServer Security Update Security Bulletin Severity: Medium Created: 26 Oct 2018 Modified: 01 Nov 2018 Applicable Products o XenServer 7.6 o XenServer 7.5 o 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: o Citrix XenServer 7.6 o Citrix XenServer 7.5 o Citrix XenServer 7.1 LTSR CU1 The following vulnerabilities have been addressed: o 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. - ------------------------------------------------------------------------------- Acknowledgements - ------------------------------------------------------------------------------- What Citrix Is Doing Citrix is notifying customers and channel partners about this potential security issue. This article is also available from the Citrix Knowledge Center at http://support.citrix.com/. - ------------------------------------------------------------------------------- Obtaining Support on This Issue If you require technical assistance with this issue, please contact Citrix Technical Support. Contact details for Citrix Technical Support are available at https://www.citrix.com/support/open-a-support-case.html. - ------------------------------------------------------------------------------- Reporting Security Vulnerabilities Citrix welcomes input regarding the security of its products and considers any and all potential vulnerabilities seriously. For guidance on how to report security-related issues to Citrix, please see the following document: CTX081743 - - Reporting Security Issues to Citrix - ------------------------------------------------------------------------------- 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 iQIVAwUBW9vWVWaOgq3Tt24GAQhvWQ//btEIrRm6/T2uExqTZud9rmTCexKmGYul VRORMiDo2+tZXjh77hqNxCNUBENPzh+/LAAjuV2UysQEt/2WS1fUx0bFxDehNVbW v4pKP3dvDhLYHuSh7FptnOkWS3yipx3bQiN4L6Np7EOj2lBfJbHMJB7TTrkKgp+p czUqzwgTW/XLaPPsx4u5fxXBOkjOouRWqMxMONGvy/l8o86q4TZsmddBYHskkJef RgUo4gGPyZVtXyNE12euGlQuvNL0QqD4NFi702zNhkYM0ITE6ZgZIw5++5QY5wi0 qeImXeuc8ayDT/U+Kyb8m4SrOz+hyH0OkVdyOhDp8KHNhr47cAnr+mue65B9IoIX FI6VA0KkPVoZIPN5BLlxYYWEgyxqQvuDPPIYgj3nmX7M6LIDFfT4biGZCwWx2vNK y+eE7n80gqDX/TcNqTfEH8se7oD23vQLZjUpaD8uuCehnmgy0XUlkMCCl4CjhRKm hsQWQFDas3Ps/LuRIwLMXfzu8jKR5hB8tI93IAY8gd6qd/gFnl1eMoi21Um/NSBK 9o5OadLzx3zk8kgwQF7AidY0fCmqo5K25FSFWV1dutdtv1Mewrv4Nm/ocLcLMggj w16wqUsdIbx1sNs2KQpTwLnXJoWFNDY8BjwMGTIZynGPY74l+BkVtBqi3pjmRGw1 qlqfVt8kLDA= =1jdQ -----END PGP SIGNATURE-----