xen: unmediated PCI command register access in qemu (xsa126)
Published Apr 1, 2015
4.9
MEDIUMCVSS 2.0
EPSS 0.45%
Description
QEMU, as used in Xen 3.3.x through 4.5.x, does not properly restrict access to PCI command registers, which might allow local HVM guest users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response.
Affected products
No data.
Configuration 1
- 7.0
- 8.0
Configuration 2
Configuration 3
- 20
- 21
Configuration 4
- 12.04
- 14.04
- 14.10
- 15.04
No data.
Red Hat Enterprise Linux 5
xen
Affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 5 | xen | Affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This issue dos affect the xen packages as shipped with Red Hat Enterprise Linux 5. Red Hat Enterprise Linux 5 is now in Production 3 Phase of the support and maintenance life cycle. This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
No CVSS v3.0 score for this CVE.
AV:L/AC:L/Au:N/C:N/I:N/A:C
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 | 0.45% (0.00450) | 36.78th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.45% (0.00454) | 35.80th | v5 (v2026.06.15) |
| Mar 17, 2025 | 0.12% (0.00122) | 28.84th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.06% (0.00064) | 30.08th | v3 (v2023.03.01) |
| Jun 21, 2024 | 0.06% (0.00064) | 28.17th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.06% (0.00064) | 26.16th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.55% (0.01547) | 74.98th | v2 (v2022.01.01) |
| Feb 23, 2023 | 1.55% (0.01547) | 74.94th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.55% (0.01547) | 72.92th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.55% (0.01547) | 51.82th | v2 (v2022.01.01) |
References (17)
- http://lists.fedoraproject.org/pipermail/package-announce/2015-April/154574.html vendor-advisoryx_refsource_FEDORA
- http://lists.fedoraproject.org/pipermail/package-announce/2015-April/154579.html vendor-advisoryx_refsource_FEDORA
- http://lists.fedoraproject.org/pipermail/package-announce/2015-April/155198.html vendor-advisoryx_refsource_FEDORA
- http://lists.nongnu.org/archive/html/qemu-devel/2015-03/msg06179.html mailing-listx_refsource_MLIST
- http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00014.html vendor-advisoryx_refsource_SUSE
- http://support.citrix.com/article/CTX201145 x_refsource_CONFIRM
- http://www.debian.org/security/2015/dsa-3259 vendor-advisoryx_refsource_DEBIAN
- http://www.securityfocus.com/bid/72577 vdb-entryx_refsource_BID
- http://www.securitytracker.com/id/1031998 vdb-entryx_refsource_SECTRACK
- http://www.ubuntu.com/usn/USN-2608-1 vendor-advisoryx_refsource_UBUNTU
- http://xenbits.xen.org/xsa/advisory-126.html x_refsource_CONFIRMVendor Advisory
- https://access.redhat.com/security/cve/CVE-2015-2756 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1203737 Issue Tracking
- https://nvd.nist.gov/vuln/detail/CVE-2015-2756
- https://security.gentoo.org/glsa/201504-04 vendor-advisoryx_refsource_GENTOO
- https://support.citrix.com/article/CTX206006 x_refsource_CONFIRM
- https://www.cve.org/CVERecord?id=CVE-2015-2756
Change history (0)
No recorded changes yet.