xen: CR0.TS and CR0.EM not always honored for x86 HVM guests (XSA-190)
Published Oct 7, 2016
6.3
MEDIUMCVSS 3.0
EPSS 0.30%
Description
Xen 4.7.x and earlier does not properly honor CR0.TS and CR0.EM, which allows local x86 HVM guest OS users to read or modify FPU, MMX, or XMM register state information belonging to arbitrary tasks on the guest by modifying an instruction while the hypervisor is preparing to emulate it.
Affected products
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
1 other source (Red Hat) ▾
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
AV:L/AC:M/Au:N/C:P/I:P/A:N
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (10 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 0.30% (0.00303) | 20.80th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.30% (0.00305) | 21.93th | v5 (v2026.06.15) |
| Mar 17, 2025 | 0.03% (0.00035) | 6.70th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.07% (0.00072) | 33.38th | v3 (v2023.03.01) |
| Jun 18, 2024 | 0.07% (0.00072) | 31.37th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.07% (0.00072) | 29.37th | v3 (v2023.03.01) |
| Mar 6, 2023 | 0.95% (0.00950) | 32.28th | v2 (v2022.01.01) |
| Sep 10, 2022 | 0.95% (0.00950) | 30.63th | v2 (v2022.01.01) |
| Apr 1, 2022 | 0.95% (0.00950) | 28.61th | v2 (v2022.01.01) |
| Feb 4, 2022 | 0.95% (0.00950) | 13.46th | v2 (v2022.01.01) |
References (9)
- http://www.securityfocus.com/bid/93344 vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
- http://www.securitytracker.com/id/1036942 vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry
- http://xenbits.xen.org/xsa/advisory-190.html x_refsource_CONFIRMMitigationPatchVendor Advisory
- https://access.redhat.com/security/cve/CVE-2016-7777 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1377789 Issue Tracking
- https://nvd.nist.gov/vuln/detail/CVE-2016-7777
- https://security.gentoo.org/glsa/201611-09 vendor-advisoryx_refsource_GENTOO
- https://support.citrix.com/article/CTX217363 x_refsource_CONFIRM
- https://www.cve.org/CVERecord?id=CVE-2016-7777
| Link | Providers | Tags |
|---|---|---|
| http://www.securityfocus.com/bid/93344 | vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry | |
| http://www.securitytracker.com/id/1036942 | vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry | |
| http://xenbits.xen.org/xsa/advisory-190.html | x_refsource_CONFIRMMitigationPatchVendor Advisory | |
| https://access.redhat.com/security/cve/CVE-2016-7777 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1377789 | Issue Tracking | |
| https://nvd.nist.gov/vuln/detail/CVE-2016-7777 | ||
| https://security.gentoo.org/glsa/201611-09 | vendor-advisoryx_refsource_GENTOO | |
| https://support.citrix.com/article/CTX217363 | x_refsource_CONFIRM | |
| https://www.cve.org/CVERecord?id=CVE-2016-7777 |
Change history (0)
No recorded changes yet.