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CVE-2020-29479

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the...

8.8 HighFix available

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.31%Down 1.0 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 8.8

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Record
CVE-2020-29479
CVSS 3.1
8.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CVSS 2.0
7.2 HighAV:L/AC:L/Au:N/C:C/I:C/A:C
Weakness
CWE-862
Updated
2026-11-02
CVE List No score

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Record
CVE-2020-29479
Updated
2026-11-02
EUVDEUVD-2020-21847 No score

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Record
EUVD-2020-21847
Updated
2026-11-03
GitHub AdvisoriesGHSA-mrwx-r54g-7x9f 8.8

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the...

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Record
GHSA-mrwx-r54g-7x9f
CVSS 3.1
8.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-732, CWE-862
Updated
2026-11-02
OSVALPINE-CVE-2020-29479 8.8

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Record
ALPINE-CVE-2020-29479
CVSS 3.1
8.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSV 8.8

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Record
CVE-2020-29479
CVSS 3.1
8.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2020-29479 8.8

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Record
DEBIAN-CVE-2020-29479
CVSS 3.1
8.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2020-29479 8.8

An issue was discovered in Xen through 4.14.x. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

Record
UBUNTU-CVE-2020-29479
CVSS 3.1
8.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
xen
Alpine:v3.11
before 4.13.2-r3
4.13.2-r3
xen
Alpine:v3.12
before 4.13.2-r3
4.13.2-r3
xen
Alpine:v3.13
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.14
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.15
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.16
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.17
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.18
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.19
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.20
before 4.14.1-r0
4.14.1-r0
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Affected packages
PackageAffectedFixed
xen
Alpine:v3.21
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.22
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.23
before 4.14.1-r0
4.14.1-r0
xen
Alpine:v3.24
before 4.14.1-r0
4.14.1-r0
xen
Debian:12
before 4.14.0+88-g1d1d1f5391-1
4.14.0+88-g1d1d1f5391-1
xen
Debian:13
before 4.14.0+88-g1d1d1f5391-1
4.14.0+88-g1d1d1f5391-1
xen
Debian:14
before 4.14.0+88-g1d1d1f5391-1
4.14.0+88-g1d1d1f5391-1
xen
Debian:10
From an advisory covering 11 CVEs
before 4.11.4+57-g41a822c392-2, plus listed versions
4.11.1+92-g6c33308a8d-24.11.3+24-g14b62ab3e5-14.11.3+24-g14b62ab3e5-1~deb10u14.11.4+24-gddaaccbbab-14.11.4+24-gddaaccbbab-1~deb10u14.11.4+37-g3263f257ca-14.11.4+57-g41a822c392-14.11.4-1
4.11.4+57-g41a822c392-2
xen
Ubuntu:16.04:LTS
All versions, plus listed versions
4.5.1-0ubuntu14.5.1-0ubuntu24.6.0-1ubuntu14.6.0-1ubuntu24.6.0-1ubuntu4
Show 7 moreShow less
4.6.0-1ubuntu4.14.6.0-1ubuntu4.24.6.0-1ubuntu4.34.6.5-0ubuntu14.6.5-0ubuntu1.14.6.5-0ubuntu1.24.6.5-0ubuntu1.4
None known
xen
Ubuntu:18.04:LTS
All versions, plus listed versions
4.9.0-0ubuntu34.9.0-0ubuntu44.9.2-0ubuntu1
None known
xen
Ubuntu:20.04:LTS
All versions, plus listed versions
4.9.2-0ubuntu24.9.2-0ubuntu64.9.2-0ubuntu74.11.3+24-g14b62ab3e5-1ubuntu14.11.3+24-g14b62ab3e5-1ubuntu24.11.3+24-g14b62ab3e5-1ubuntu2.24.11.3+24-g14b62ab3e5-1ubuntu2.3
None known

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-29479 is a high vulnerability (CVSS 8.8) in Xen, published December 15, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.31%, the 23rd percentile. Fixed in xen 4.13.2-r3.

References

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