An issue was discovered in Xen through 4.14.x.
An issue was discovered in Xen through 4.14.x. When they require assistance from the device model, x86 HVM guests must be temporarily de-scheduled. The device model will signal Xen when it has completed its operation, via an event channel, so that the relevant vCPU is rescheduled. If the device model were to signal Xen without having actually completed the operation, the de-schedule / re-schedule cycle would repeat. If, in addition, Xen is resignalled very quickly, the re-schedule may occur before the de-schedule was fully complete, triggering a shortcut. This potentially repeating process uses ordinary recursive function calls, and thus could result in a stack overflow. A malicious or buggy stubdomain serving a HVM guest can cause Xen to crash, resulting in a Denial of Service (DoS) to the entire host. Only x86 systems are affected. Arm systems are not affected. Only x86 stubdomains serving HVM guests can exploit the vulnerability.
- Published
- Dec 15, 2020
- Updated
- Jun 16, 2026
- EPSS
- 0.4% · 36th percentile
- CWE
- CWE-674
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Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 22 / 40 · 5.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; 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 helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| xen | xen | cpe:2.3:o:xen:xen |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux10.0
- fedoraproject fedora32
- fedoraproject fedora33
- xen xenup to 4.14.0 inclusive
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.11 | xen | before 4.13.2-r3 | 4.13.2-r3 |
| Alpine:v3.13 | xen | before 4.14.1-r0 | 4.14.1-r0 |
| Debian:10 | xen | before 4.11.4+57-g41a822c392-2 | 4.11.4+57-g41a822c392-2 |
| Debian:12 | xen | before 4.14.0+88-g1d1d1f5391-1 | 4.14.0+88-g1d1d1f5391-1 |
| openSUSE:Leap 15.1 | xen | before 4.12.4_06-lp151.2.36.1 | 4.12.4_06-lp151.2.36.1 |
| openSUSE:Leap 15.2 | xen | before 4.13.2_06-lp152.2.21.1 | 4.13.2_06-lp152.2.21.1 |
| SUSE:HPE Helion OpenStack 8 | xen | before 4.9.4_16-3.80.1 | 4.9.4_16-3.80.1 |
| SUSE:Linux Enterprise High Performance Computing 15-ESPOS | xen | before 4.10.4_24-3.53.1 | 4.10.4_24-3.53.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP1 | xen | before 4.12.4_06-3.40.1 | 4.12.4_06-3.40.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP2 | xen | before 4.13.2_06-3.22.1 | 4.13.2_06-3.22.1 |
| SUSE:Linux Enterprise Server 11 SP4-LTSS | xen | before 4.4.4_48-61.61.1 | 4.4.4_48-61.61.1 |
| SUSE:Linux Enterprise Software Development Kit 12 SP5 | xen | before 4.12.4_06-3.36.1 | 4.12.4_06-3.36.1 |
| SUSE:OpenStack Cloud 7 | xen | before 4.7.6_14-43.73.1 | 4.7.6_14-43.73.1 |
| SUSE:OpenStack Cloud 9 | xen | before 4.11.4_16-2.48.1 | 4.11.4_16-2.48.1 |
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 |
|---|---|---|
| alpine:xen | 4.13.2-r3 · Alpine:v3.11 | Package registry (OSV) |
| debian:xen | 4.14.0+88-g1d1d1f5391-1 · Debian:12 | Package registry (OSV) |
| opensuse:xen | 4.12.4_06-lp151.2.36.1 · openSUSE:Leap 15.1 | Package registry (OSV) |
| suse:xen | 4.4.4_48-61.61.1 · SUSE:Linux Enterprise Server 11 SP4-LTSS | 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.
No commit or PR link among the references.
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).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-20-1043 · Dec 18, 2020(Xen Zafiyeti)
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
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-674 · Uncontrolled RecursionCVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvd-primary
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)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2C6M6S3CIMEBACH6O7V4H2VDANMO6TVA/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OBLV6L6Q24PPQ2CRFXDX4Q76KU776GKI/
- security.gentoo.org/glsa/202107-30
- www.debian.org/security/2020/dsa-4812
- xenbits.xenproject.org/xsa/advisory-348.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.