An issue was discovered in Xen 4.11.x allowing x86 guest OS users to cause a denial of service (host OS hang) because the p2m lock remains unavailable indefinitely in certain error conditions.

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - An issue was discovered in Xen through 4.11.x allowing x86 PV guest OS users to cause a denial of service
    (host OS crash) or possibly gain host OS privileges because of an interpretation conflict for a union data
    structure associated with shadow paging. NOTE: this issue exists because of an incorrect fix for
    CVE-2017-15595. (CVE-2018-19966)

  - Systems with microprocessors utilizing speculative execution and address translations may allow
    unauthorized disclosure of information residing in the L1 data cache to an attacker with local user access
    via a terminal page fault and a side-channel analysis. (CVE-2018-3620)

  - Systems with microprocessors utilizing speculative execution and address translations may allow
    unauthorized disclosure of information residing in the L1 data cache to an attacker with local user access
    with guest OS privilege via a terminal page fault and a side-channel analysis. (CVE-2018-3646)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - An issue was discovered in Xen 4.11.x allowing x86 guest OS users to cause a denial of service (host OS     hang) because the p2m lock remains unavailable indefinitely in certain error conditions. (CVE-2018-19964)

Note that Nessus relies on the presence of the package as reported by the vendor.

This update for xen fixes the following issues :

Update to Xen 4.11.1 bug fix release (bsc#1027519)

CVE-2018-17963: Fixed an integer overflow issue in the QEMU emulator, which could occur when a packet with large packet size is processed. A user inside a guest could have used this flaw to crash the qemu process resulting in a Denial of Service (DoS). (bsc#1111014)

CVE-2018-18849: Fixed an out of bounds memory access in the LSI53C895A SCSI host bus adapter emulation, which allowed a user and/or process to crash the qemu process resulting in a Denial of Service (DoS).
(bsc#1114423)

CVE-2018-18883: Fixed an issue related to inproper restriction of nested VT-x, which allowed a guest to cause Xen to crash, resulting in a Denial of Service (DoS). (XSA-278) (bsc#1114405)

CVE-2018-19961, CVE-2018-19962: Fixed an issue related to insufficient TLB flushing with AMD IOMMUs, which potentially allowed a guest to escalate its privileges, may cause a Denial of Service (DoS) affecting the entire host, or may be able to access data it is not supposed to access. (XSA-275) (bsc#1115040)

CVE-2018-19963: Fixed the allocation of pages used to communicate with external emulators, which may have cuased Xen to crash, resulting in a Denial of Service (DoS). (XSA-276) (bsc#1115043)

CVE-2018-19965: Fixed an issue related to the INVPCID instruction in case non-canonical addresses are accessed, which may allow a guest to cause Xen to crash, resulting in a Denial of Service (DoS) affecting the entire host. (XSA-279) (bsc#1115045)

CVE-2018-19966: Fixed an issue related to a previous fix for XSA-240, which conflicted with shadow paging and allowed a guest to cause Xen to crash, resulting in a Denial of Service (DoS) (XSA-280) (bsc#1115047)

CVE-2018-19967: Fixed HLE constructs that allowed guests to lock up the host, resulting in a Denial of Service (DoS). (XSA-282) (bsc#1114988)

CVE-2018-19964: Fixed the incorrect error handling of p2m page removals, which allowed a guest to cause a deadlock, resulting in a Denial of Service (DoS) affecting the entire host. (XSA-277) (bsc#1115044)

CVE-2018-19665: Fixed an integer overflow resulting in memory corruption in various Bluetooth functions, allowing this to crash qemu process resulting in Denial of Service (DoS). (bsc#1117756).

Other bugs fixed: Fixed an issue related to a domU hang on SLE12-SP3 HV (bsc#1108940)

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a guest-to-host denial of service vulnerability. An attacker located on a guest virtual machine may be able to exploit this vulnerability to affect the availability of the host system. Only x86 systems running untrusted HVM or PVH guests are considered vulnerable.

Note that Nessus has checked the changeset versions based on the xen.git change log. Nessus did not check guest hardware configurations or if patches were applied manually to the source code before a recompile and reinstall.

ID	Name	Product	Family	Type	Severity
424700	Alpine: multiple xen packages: security update to 4.11.1-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	Local	high
424700	Alpine: multiple xen packages: security update to 4.11.1-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	Local	high
222110	Linux Distros Unpatched Vulnerability : CVE-2018-19964	Nessus	Misc.	Local	medium
120983	SUSE SLED12 / SLES12 Security Update : xen (SUSE-SU-2019:0003-1)	Nessus	SuSE Local Security Checks	Local	critical
119658	Xen Project Guest p2m Page Removal Error Handling DoS (XSA-277)	Nessus	Misc.	Local	medium

Detections

Analytics

CVE-2018-19964

medium

Tenable Plugins

high

high

medium

critical

medium