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Fencer Vulns
high 8.8

CVE-2020-29479 json

An issue was discovered in Xen through 4.14.x.

published 2020-12-15 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-21847

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits
0
none known

Summary

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.

Patch / fix

  • xen Debian 14, Debian 13, Debian 12 4.14.0+88-g1d1d1f5391-1

debian advisories DEBIAN-CVE-2020-29479

  • xen Alpine 3.12, Alpine 3.11 4.13.2-r3
  • xen Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 4.14.1-r0

alpine advisories ALPINE-CVE-2020-29479

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-29479 updated cvss 7.0

xen: oxenstored: permissions not checked on root node (XSA-353)

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.31% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD 2.0 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.