The fpu_fxrstor function in arch/x86/i387.c in Xen 4.x does not properly handle writes to the hardware FSW.ES bit when running on AMD64 proc
The fpu_fxrstor function in arch/x86/i387.c in Xen 4.x does not properly handle writes to the hardware FSW.ES bit when running on AMD64 processors, which allows local guest OS users to obtain sensitive register content information from another guest by leveraging pending exception and mask bits. NOTE: this vulnerability exists because of an incorrect fix for CVE-2013-2076.
- Published
- Apr 13, 2016
- Updated
- Jun 16, 2026
- EPSS
- 0.4% · 32th percentile
- CWE
- CWE-200
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Report tools
Action score
15
Monitor
Low priority for now.
- CVSS
- 15 / 40 · 3.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| xen | xen | cpe:2.3:o:xen:xen |
| oracle | vm server | cpe:2.3:o:oracle:vm_server |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux8.0
- fedoraproject fedora22
- fedoraproject fedora23
- oracle vm server3.3
- oracle vm server3.4
- xen xen4.5.0 and later · up to 4.5.3 inclusive
- xen xen4.6.0 and later · up to 4.6.1 inclusive
- xen xen4.4.0 and later · up to 4.4.4 inclusive
- xen xen4.3.0 and later · up to 4.3.4 inclusive
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | xen | before 4.8.0~rc3-1 | 4.8.0~rc3-1 |
| Debian:7 | xen | before 4.1.6.lts1-1 | 4.1.6.lts1-1 |
| Debian:8 | xen | before 4.4.1-9+deb8u5 | 4.4.1-9+deb8u5 |
| SUSE:Linux Enterprise Desktop 12 SP1 | xen | before 4.5.3_08-17.1 | 4.5.3_08-17.1 |
| SUSE:Linux Enterprise Server 11 SP2-LTSS | xen | before 4.1.6_08-29.1 | 4.1.6_08-29.1 |
| SUSE:Linux Enterprise Server for SAP Applications 12 | xen | before 4.4.4_04-22.22.2 | 4.4.4_04-22.22.2 |
| SUSE:Linux Enterprise Software Development Kit 11 SP4 | xen | before 4.4.4_07-37.1 | 4.4.4_07-37.1 |
| SUSE:OpenStack Cloud 5 | xen | before 4.2.5_21-27.1 | 4.2.5_21-27.1 |
Same product
xen: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-10921The grant-table feature in Xen through 4.8.x does not ensure sufficient type counts for a GNTMAP_device_map and GNTMAP_host_map mapping, whi41Plan
- CVE-2017-10920The grant-table feature in Xen through 4.8.x mishandles a GNTMAP_device_map and GNTMAP_host_map mapping, when followed by only a GNTMAP_host41Plan
- CVE-2017-10918Xen through 4.8.x does not validate memory allocations during certain P2M operations, which allows guest OS users to obtain privileged host 41Plan
- CVE-2017-10912Xen through 4.8.x mishandles page transfer, which allows guest OS users to obtain privileged host OS access, aka XSA-217.41Plan
- CVE-2015-8104The KVM subsystem in the Linux kernel through 4.2.6, and Xen 4.3.x through 4.6.x, allows guest OS users to cause a denial of service (host O41Plan
- CVE-2015-5165The C+ mode offload emulation in the RTL8139 network card device model in QEMU, as used in Xen 4.5.x and earlier, allows remote attackers to41Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:xen | 4.8.0~rc3-1 · Debian:12 | Package registry (OSV) |
| suse:xen | 4.5.3_08-17.1 · SUSE:Linux Enterprise Desktop 12 SP1 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- none
- Availability
- none
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- Low
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-200 · Exposure of Sensitive Information to an Unauthorized ActorCVSS vector
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
nvd-primary
Root cause
The extension requests broader permissions than its function needs and sends the data it collects out for purposes beyond its stated function.
The bug in code
The whole CWE-200 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
{ "permissions": ["tabs", "<all_urls>"], "background": { "service_worker": "analytics.js" }}Fixed
{ "permissions": ["activeTab"], "host_permissions": ["https://yildiz.example/*"]}Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- ExcavationCAPEC-116likelihood: High · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
- FootprintingCAPEC-169likelihood: High · Very Low
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- FingerprintingCAPEC-224likelihood: High · Very Low
- ICMP Echo Request PingCAPEC-285likelihood: Medium · Low
- TCP SYN ScanCAPEC-287Low
- Enumerate Mail Exchange (MX) RecordsCAPEC-290Low
ATT&CK techniques
- System Service DiscoveryT1007
- System Network Configuration DiscoveryT1016
- Remote System DiscoveryT1018
- System Owner/User DiscoveryT1033
- Masquerading: Match Legitimate Name or LocationT1036.005
- Network Service ScanningT1046
- System Network Connections DiscoveryT1049
- Process DiscoveryT1057
- Permission Groups DiscoveryT1069
- System Information DiscoveryT1082
- File and Directory DiscoveryT1083
- Account DiscoveryT1087
- Multi-Factor Authentication InterceptionT1111
- Peripheral Device DiscoveryT1120
- System Time DiscoveryT1124
- Access Token Manipulation:Token Impersonation/TheftT1134.001
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
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References
- lists.fedoraproject.org/pipermail/package-announce/2016-April/181699.html
- lists.fedoraproject.org/pipermail/package-announce/2016-April/181729.html
- support.citrix.com/article/CTX209443
- www.debian.org/security/2016/dsa-3554
- www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
- www.securityfocus.com/bid/85716
- www.securitytracker.com/id/1035435
- xenbits.xen.org/xsa/advisory-172.html
- xenbits.xen.org/xsa/xsa172.patch
Vendor advisories and official records. Exploit/PoC links are deliberately left out.