#VU40713 Resource management error in Xen - CVE-2015-4164

Vulnerability identifier: #VU40713

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2015-4164

CWE-ID: CWE-399

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Xen
Server applications / Virtualization software

Vendor: Xen Project

Description

The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.

The compat_iret function in Xen 3.1 through 4.5 iterates the wrong way through a loop, which allows local 32-bit PV guest administrators to cause a denial of service (large loop and system hang) via a hypercall_iret call with EFLAGS.VM set.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Xen: 3.1.3 - 4.5.0

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External links
https://lists.opensuse.org/opensuse-security-announce/2015-06/msg00004.html
https://lists.opensuse.org/opensuse-security-announce/2015-06/msg00007.html
https://lists.opensuse.org/opensuse-security-announce/2015-06/msg00029.html
https://lists.opensuse.org/opensuse-security-announce/2015-06/msg00030.html
https://lists.opensuse.org/opensuse-security-announce/2015-07/msg00014.html
https://lists.opensuse.org/opensuse-security-announce/2015-09/msg00027.html
https://support.citrix.com/article/CTX201145
https://www.debian.org/security/2015/dsa-3286
https://www.securityfocus.com/bid/75149
https://www.securitytracker.com/id/1032569
https://xenbits.xen.org/xsa/advisory-136.html
https://security.gentoo.org/glsa/201604-03

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.