NVD / CVE Program· CNA mitre

CVE-2020-15565: An issue was discovered in Xen through 4.13.x, allowing x86 Intel HVM guest OS users to cause a host OS denial of service or possibly gain p

Noroxi assessment

Priority: Monitor (action score 35/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.36% (FIRST EPSS).
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.
Fixed version: xen (Alpine:v3.10) 4.12.3-r2; xen (Alpine:v3.11) 4.13.1-r2; xen (Alpine:v3.13) 4.13.1-r4.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to xen (Alpine:v3.10) 4.12.3-r2; xen (Alpine:v3.11) 4.13.1-r2; xen (Alpine:v3.13) 4.13.1-r4 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

An issue was discovered in Xen through 4.13.x, allowing x86 Intel HVM guest OS users to cause a host OS denial of service or possibly gain privileges because of insufficient cache write-back under VT-d. When page tables are shared between IOMMU and CPU, changes to them require flushing of both TLBs. Furthermore, IOMMUs may be non-coherent, and hence prior to flushing IOMMU TLBs, a CPU cache also needs writing back to memory after changes were made. Such writing back of cached data was missing in particular when splitting large page mappings into smaller granularity ones. A malicious guest may be able to retain read/write DMA access to frames returned to Xen's free pool, and later reused for another purpose. Host crashes (leading to a Denial of Service) and privilege escalation cannot be ruled out. Xen versions from at least 3.2 onwards are affected. Only x86 Intel systems are affected. x86 AMD as well as Arm systems are not affected. Only x86 HVM guests using hardware assisted paging (HAP), having a passed through PCI device assigned, and having page table sharing enabled can leverage the vulnerability. Note that page table sharing will be enabled (by default) only if Xen considers IOMMU and CPU large page size support compatible.

HighCVSS 8.8 · v3.1—No exploit Fix available

Published: Jul 7, 2020
Updated: Jun 16, 2026
EPSS: 0.3% · 29th percentile
CWE: CWE-400

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 35 / 40 · 8.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.3%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

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
opensuse	leap	cpe:2.3:o:opensuse:leap

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 fedora31
fedoraproject fedora32
opensuse leap15.1
opensuse leap15.2
xen xen3.2.0 and later · up to 4.13.1 inclusive

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Alpine:v3.10	xen	from 3.2.0 · before 4.12.3-r2	4.12.3-r2
Alpine:v3.11	xen	from 3.2.0 · before 4.13.1-r2	4.13.1-r2
Alpine:v3.13	xen	from 3.2.0 · before 4.13.1-r4	4.13.1-r4
Alpine:v3.9	xen	from 3.2.0 · before 4.11.4-r0	4.11.4-r0
Debian:10	xen	before 4.11.4+24-gddaaccbbab-1~deb10u1	4.11.4+24-gddaaccbbab-1~deb10u1
Debian:12	xen	before 4.11.4+24-gddaaccbbab-1	4.11.4+24-gddaaccbbab-1
openSUSE:Leap 15.1	xen	before 4.12.3_04-lp151.2.21.1	4.12.3_04-lp151.2.21.1
openSUSE:Leap 15.2	xen	before 4.13.1_04-lp152.2.3.1	4.13.1_04-lp152.2.3.1
SUSE:HPE Helion OpenStack 8	xen	before 4.9.4_08-3.66.1	4.9.4_08-3.66.1
SUSE:Linux Enterprise High Performance Computing 15-ESPOS	xen	before 4.10.4_12-3.35.1	4.10.4_12-3.35.1
SUSE:Linux Enterprise Module for Basesystem 15 SP1	xen	before 4.12.3_04-3.22.1	4.12.3_04-3.22.1
SUSE:Linux Enterprise Module for Basesystem 15 SP2	xen	before 4.13.1_04-3.4.1	4.13.1_04-3.4.1
SUSE:Linux Enterprise Server 11 SP4-LTSS	xen	before 4.4.4_44-61.55.1	4.4.4_44-61.55.1
SUSE:Linux Enterprise Software Development Kit 12 SP5	xen	before 4.12.3_04-3.18.1	4.12.3_04-3.18.1
SUSE:OpenStack Cloud 7	xen	before 4.7.6_10-43.67.1	4.7.6_10-43.67.1
SUSE:OpenStack Cloud 9	xen	before 4.11.4_04-2.30.1	4.11.4_04-2.30.1

Same product

xen: all records

Other 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, whi
41Plan
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_host
41Plan
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

Published before and after this one in the same product

← EarlierCVE-2020-15563Jul 7, 2020 · An issue was discovered in Xen through 4.13.x, allowing x86 HVM guest OS users to cause a hypervisor crash.
26Monitor
← EarlierCVE-2020-15564Jul 7, 2020 · An issue was discovered in Xen through 4.13.x, allowing Arm guest OS users to cause a hypervisor crash because of a missing alignment check
26Monitor
Later →CVE-2020-15566Jul 7, 2020 · An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a host OS crash because of incorrect error handling in event
26Monitor

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	4.12.3-r2 · Alpine:v3.10	Package registry (OSV)
debian:xen	4.11.4+24-gddaaccbbab-1 · Debian:12	Package registry (OSV)
opensuse:xen	4.12.3_04-lp151.2.21.1 · openSUSE:Leap 15.1	Package registry (OSV)
suse:xen	4.4.4_44-61.55.1 · 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.

EPSS, last 120 days

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 researchers

Finders, 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-20-505 · Jul 8, 2020(Xen Zafiyeti)

All national notices →

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: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

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: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

nvd-primary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

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

Endpoint Denial of ServiceT1499

Change log

Fix✗ → ✓Sep 28, 2026, 10:48 PM UTC

For records you follow, these changes also arrive as notifications. →

References

lists.opensuse.org/opensuse-security-announce/2020-07/msg00024.html

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records