|Public release ||2015-03-10 12:00|
|Updated ||2015-03-10 12:00|
|Title ||Hypervisor memory corruption due to x86 emulator flaw|
Filesadvisory-123.txt (signed advisory file)
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Xen Security Advisory CVE-2015-2151 / XSA-123
Hypervisor memory corruption due to x86 emulator flaw
UPDATES IN VERSION 4
Instructions with register operands ignore eventual segment overrides
encoded for them. Due to an insufficiently conditional assignment such
a bogus segment override can, however, corrupt a pointer used
subsequently to store the result of the instruction.
A malicious guest might be able to read sensitive data relating to
other guests, or to cause denial of service on the host. Arbitrary code
execution, and therefore privilege escalation, cannot be excluded.
Xen 3.2.x and later are vulnerable.
Xen 3.1.x and earlier have not been inspected.
Only x86 systems are vulnerable. ARM systems are not vulnerable.
There is no mitigation available for this issue.
This issue was discovered by Felix Wilhelm of ERNW GmbH.
Applying the appropriate attached patch resolves this issue.
xsa123.patch xen-unstable, Xen 4.5.x, Xen 4.4.x
xsa123-4.3-4.2.patch Xen 4.3.x, Xen 4.2.x
$ sha256sum xsa123*.patch
DEPLOYMENT DURING EMBARGO
Deployment of the patches and/or mitigations described above (or
others which are substantially similar) is permitted during the
embargo, even on public-facing systems with untrusted guest users and
But: Distribution of updated software is prohibited (except to other
members of the predisclosure list).
Predisclosure list members who wish to deploy significantly different
patches and/or mitigations, please contact the Xen Project Security
(Note: this during-embargo deployment notice is retained in
post-embargo publicly released Xen Project advisories, even though it
is then no longer applicable. This is to enable the community to have
oversight of the Xen Project Security Team's decisionmaking.)
For more information about permissible uses of embargoed information,
consult the Xen Project community's agreed Security Policy:
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Xenproject.org Security Team