An issue was discovered in Xen through 4.11.x, allowing x86 Intel HVM guest OS users to achieve unintended read/write DMA access, and possibly cause a denial of service (host OS crash) or gain privileges. This occurs because a backport missed a flush, and thus IOMMU updates were not always correct. NOTE: this issue exists because of an incomplete fix for CVE-2020-15565.

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 through 4.11.x, allowing x86 Intel HVM guest OS users to achieve unintended     read/write DMA access, and possibly cause a denial of service (host OS crash) or gain privileges. This     occurs because a backport missed a flush, and thus IOMMU updates were not always correct. NOTE: this issue     exists because of an incomplete fix for CVE-2020-15565. (CVE-2021-27379)

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

This update for xen fixes the following issues :

CVE-2021-27379: Fixed an issue where entries in the IOMMU were not being updated under certain circumstances due to improper backport of XSA-321 (XSA-366, bsc#1182431)

Fixed an issue where xenstored was crashing with segfault (bsc#1182155).

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 an issue allowing x86 Intel HVM guest OS users to achieve unintended read/write DMA access, and possibly cause a denial of service (host OS crash) or gain privileges. This occurs because a backport missed a flush, and thus IOMMU updates were not always correct. NOTE: this issue exists because of an incomplete fix for CVE-2020-15565.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version   number.

This update for xen fixes the following issues :

CVE-2021-27379: Fixed an issue where entries in the IOMMU were not being updated under certain circumstances due to improper backport of XSA-321 (XSA-366, bsc#1182431)

CVE-2021-20257: Fixed an infinite loop in the e1000 NIC emulator (bsc#1182846)

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.

This update for xen fixes the following issues :

CVE-2021-20257: xen: infinite loop issue in the e1000 NIC emulator (bsc#1182846).

CVE-2021-27379: Fixed an issue where entries in the IOMMU were not being updated under certain circumstances due to improper backport of XSA-321 (XSA-366, bsc#1182431).

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.

Multiple vulnerabilities have been discovered in the Xen hypervisor, which could result in denial of service, privilege escalation or memory disclosure.

ID	Name	Product	Family	Severity
257001	Linux Distros Unpatched Vulnerability : CVE-2021-27379	Nessus	Misc.	high
148864	SUSE SLES12 Security Update : xen (SUSE-SU-2021:1268-1)	Nessus	SuSE Local Security Checks	high
148843	Xen Missed Flush DoS or Privilege Escalation (XSA-366)	Nessus	Misc.	high
148838	SUSE SLES12 Security Update : xen (SUSE-SU-2021:1251-1)	Nessus	SuSE Local Security Checks	high
148837	SUSE SLES12 Security Update : xen (SUSE-SU-2021:1252-1)	Nessus	SuSE Local Security Checks	high
148444	Debian DSA-4888-1 : xen - security update	Nessus	Debian Local Security Checks	high

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CVE-2021-27379

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