Multiple vulnerabilities in Xen
| Risk | Medium |
| Patch available | YES |
| Number of vulnerabilities | 6 |
| CVE-ID | CVE-2019-19577 CVE-2019-19580 CVE-2019-19578 CVE-2019-19583 CVE-2019-19581 CVE-2019-19582 |
| CWE-ID | CWE-20 CWE-362 CWE-399 CWE-835 |
| Exploitation vector | Local network |
| Public exploit | N/A |
| Vulnerable software Subscribe |
Xen Server applications / Virtualization software |
| Vendor | Xen Project |
Security Bulletin
This security bulletin contains information about 6 vulnerabilities.
1) Input validation error
EUVDB-ID: #VU31976
Risk: Low
CVSSv3.1: 5.4 [CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2019-19577
CWE-ID:
CWE-20 - Improper input validation
Exploit availability: No
DescriptionThe vulnerability allows a remote user to perform a denial of service (DoS) attack.
An issue was discovered in Xen through 4.12.x allowing x86 AMD HVM guest OS users to cause a denial of service or possibly gain privileges by triggering data-structure access during pagetable-height updates. When running on AMD systems with an IOMMU, Xen attempted to dynamically adapt the number of levels of pagetables (the pagetable height) in the IOMMU according to the guest's address space size. The code to select and update the height had several bugs. Notably, the update was done without taking a lock which is necessary for safe operation. A malicious guest administrator can cause Xen to access data structures while they are being modified, causing Xen to crash.
MitigationInstall updates from vendor's website.
Vulnerable software versionsXen: 4.8.0 - 4.12.0
External linkshttp://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
http://seclists.org/bugtraq/2020/Jan/21
http://security.gentoo.org/glsa/202003-56
http://www.debian.org/security/2020/dsa-4602
http://xenbits.xen.org/xsa/advisory-311.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated privileged user via the local network (LAN).
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
2) Race condition
EUVDB-ID: #VU31977
Risk: Low
CVSSv3.1: 6.6 [CVSS:3.1/AV:A/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2019-19580
Exploit availability: No
DescriptionThe vulnerability allows a local user to escalate privileges on the system.
An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to gain host OS privileges by leveraging race conditions in pagetable promotion and demotion operations, because of an incomplete fix for CVE-2019-18421. XSA-299 addressed several critical issues in restartable PV type change operations. Despite extensive testing and auditing, some corner cases were missed. A malicious PV guest administrator may be able to escalate their privilege to that of the host. All security-supported versions of Xen are vulnerable. Only x86 systems are affected. Arm systems are not affected. Only x86 PV guests can leverage the vulnerability. x86 HVM and PVH guests cannot leverage the vulnerability. Note that these attacks require very precise timing, which may be difficult to exploit in practice.
MitigationInstall updates from vendor's website.
Vulnerable software versionsXen: 4.9.0 - 4.12.0
External linkshttp://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
http://seclists.org/bugtraq/2020/Jan/21
http://security.gentoo.org/glsa/202003-56
http://www.debian.org/security/2020/dsa-4602
http://xenbits.xen.org/xsa/advisory-310.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated privileged user via the local network (LAN).
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
3) Input validation error
EUVDB-ID: #VU31978
Risk: Medium
CVSSv3.1: 5.9 [CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2019-19578
CWE-ID:
CWE-20 - Improper input validation
Exploit availability: No
DescriptionThe vulnerability allows a remote user to perform a denial of service (DoS) attack.
An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to cause a denial of service via degenerate chains of linear pagetables, because of an incorrect fix for CVE-2017-15595. "Linear pagetables" is a technique which involves either pointing a pagetable at itself, or to another pagetable of the same or higher level. Xen has limited support for linear pagetables: A page may either point to itself, or point to another pagetable of the same level (i.e., L2 to L2, L3 to L3, and so on). XSA-240 introduced an additional restriction that limited the "depth" of such chains by allowing pages to either *point to* other pages of the same level, or *be pointed to* by other pages of the same level, but not both. To implement this, we keep track of the number of outstanding times a page points to or is pointed to another page table, to prevent both from happening at the same time. Unfortunately, the original commit introducing this reset this count when resuming validation of a partially-validated pagetable, incorrectly dropping some "linear_pt_entry" counts. If an attacker could engineer such a situation to occur, they might be able to make loops or other arbitrary chains of linear pagetables, as described in XSA-240. A malicious or buggy PV guest may cause the hypervisor to crash, resulting in Denial of Service (DoS) affecting the entire host. Privilege escalation and information leaks cannot be excluded. All versions of Xen are vulnerable. Only x86 systems are affected. Arm systems are not affected. Only x86 PV guests can leverage the vulnerability. x86 HVM and PVH guests cannot leverage the vulnerability. Only systems which have enabled linear pagetables are vulnerable. Systems which have disabled linear pagetables, either by selecting CONFIG_PV_LINEAR_PT=n when building the hypervisor, or adding pv-linear-pt=false on the command-line, are not vulnerable.
MitigationInstall updates from vendor's website.
Vulnerable software versionsXen: 4.8.0 - 4.12.1
External linkshttp://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
http://seclists.org/bugtraq/2020/Jan/21
http://security.gentoo.org/glsa/202003-56
http://www.debian.org/security/2020/dsa-4602
http://xenbits.xen.org/xsa/advisory-309.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
4) Resource management error
EUVDB-ID: #VU31979
Risk: Medium
CVSSv3.1: 5.9 [CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2019-19583
CWE-ID:
CWE-399 - Resource Management Errors
Exploit availability: No
DescriptionThe vulnerability allows a remote user to perform a denial of service (DoS) attack.
An issue was discovered in Xen through 4.12.x allowing x86 HVM/PVH guest OS users to cause a denial of service (guest OS crash) because VMX VMEntry checks mishandle a certain case. Please see XSA-260 for background on the MovSS shadow. Please see XSA-156 for background on the need for #DB interception. The VMX VMEntry checks do not like the exact combination of state which occurs when #DB in intercepted, Single Stepping is active, and blocked by STI/MovSS is active, despite this being a legitimate state to be in. The resulting VMEntry failure is fatal to the guest. HVM/PVH guest userspace code may be able to crash the guest, resulting in a guest Denial of Service. All versions of Xen are affected. Only systems supporting VMX hardware virtual extensions (Intel, Cyrix, or Zhaoxin CPUs) are affected. Arm and AMD systems are unaffected. Only HVM/PVH guests are affected. PV guests cannot leverage the vulnerability.
MitigationInstall updates from vendor's website.
Vulnerable software versionsXen: 4.8.0 - 4.12.1
External linkshttp://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
http://seclists.org/bugtraq/2020/Jan/21
http://security.gentoo.org/glsa/202003-56
http://www.debian.org/security/2020/dsa-4602
http://xenbits.xen.org/xsa/advisory-308.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
5) Resource management error
EUVDB-ID: #VU31980
Risk: Medium
CVSSv3.1: 5.9 [CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2019-19581
CWE-ID:
CWE-399 - Resource Management Errors
Exploit availability: No
DescriptionThe vulnerability allows a remote user to perform a denial of service (DoS) attack.
An issue was discovered in Xen through 4.12.x allowing 32-bit Arm guest OS users to cause a denial of service (out-of-bounds access) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On 32-bit Arm accesses to bitmaps with bit a count which is a multiple of 32, an out of bounds access may occur. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. 32-bit Arm systems are vulnerable. 64-bit Arm systems are not vulnerable.
MitigationInstall updates from vendor's website.
Vulnerable software versionsXen: 4.8.0 - 4.12.1
External linkshttp://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
http://seclists.org/bugtraq/2020/Jan/21
http://security.gentoo.org/glsa/202003-56
http://www.debian.org/security/2020/dsa-4602
http://xenbits.xen.org/xsa/advisory-307.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
6) Infinite loop
EUVDB-ID: #VU31981
Risk: Medium
CVSSv3.1: 5.9 [CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2019-19582
CWE-ID:
CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')
Exploit availability: No
DescriptionThe vulnerability allows a remote user to perform a denial of service (DoS) attack.
An issue was discovered in Xen through 4.12.x allowing x86 guest OS users to cause a denial of service (infinite loop) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On x86 accesses to bitmaps with a compile time known size of 64 may incur undefined behavior, which may in particular result in infinite loops. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. x86 systems with 64 or more nodes are vulnerable (there might not be any such systems that Xen would run on). x86 systems with less than 64 nodes are not vulnerable.
MitigationInstall updates from vendor's website.
Vulnerable software versionsXen: 4.8.0 - 4.12.1
External linkshttp://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
http://seclists.org/bugtraq/2020/Jan/21
http://security.gentoo.org/glsa/202003-56
http://www.debian.org/security/2020/dsa-4602
http://xenbits.xen.org/xsa/advisory-307.html
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
