Skip to content
Fencer Intel
high 8.8

CVE-2019-18423 json

An issue was discovered in Xen through 4.12.x allowing ARM guest OS users to cause a denial of service via a XENMEM_add_to_physmap hypercal…

published 7y ago modified 4mo ago also EUVD-2019-8192

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

An issue was discovered in Xen through 4.12.x allowing ARM guest OS users to cause a denial of service via a XENMEM_add_to_physmap hypercall. p2m->max_mapped_gfn is used by the functions p2m_resolve_translation_fault() and p2m_get_entry() to sanity check guest physical frame. The rest of the code in the two functions will assume that there is a valid root table and check that with BUG_ON(). The function p2m_get_root_pointer() will ignore the unused top bits of a guest physical frame. This means that the function p2m_set_entry() will alias the frame. However, p2m->max_mapped_gfn will be updated using the original frame. It would be possible to set p2m->max_mapped_gfn high enough to cover a frame that would lead p2m_get_root_pointer() to return NULL in p2m_get_entry() and p2m_resolve_translation_fault(). Additionally, the sanity check on p2m->max_mapped_gfn is off-by-one allowing "highest mapped + 1" to be considered valid. However, p2m_get_root_pointer() will return NULL. The problem could be triggered with a specially crafted hypercall XENMEM_add_to_physmap{, _batch} followed by an access to an address (via hypercall or direct access) that passes the sanity check but cause p2m_get_root_pointer() to return NULL. A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen version 4.8 and newer are vulnerable. Only Arm systems are vulnerable. x86 systems are not affected.

Patch / fix

  • xen Debian 14, Debian 13, Debian 12 4.11.3+24-g14b62ab3e5-1

debian advisories DEBIAN-CVE-2019-18423

  • xen SLES for SAP 12 SP4, SLES 12 SP4, SLED 12 SP4 +1 more 4.11.3_02-2.20.1
  • xen SLE Module for Server Applications 15, SLE Module for Basesystem 15 4.10.4_08-3.28.1
  • xen SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +4 more 4.9.4_06-3.59.1
  • xen SLE Module for Server Applications 15 SP1, SLE Module for Basesystem 15 SP1 4.12.1_04-3.6.1

suse advisories SUSE-SU-2019:3310-1SUSE-SU-2019:3309-1SUSE-SU-2019:3297-1SUSE-SU-2019:2961-1

  • xen Alpine 3.10 4.12.1-r1
  • xen Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 4.13.0-r0
  • xen Alpine 3.8 4.10.4-r1
  • xen Alpine 3.9 4.11.2-r1

alpine advisories ALPINE-CVE-2019-18423

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

Is CVE-2019-18423 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2019-18423 updated cvss 5.8

xen: add-to-physmap can be abused to DoS Arm hosts

  • Red Hat Enterprise Linux 5 kernel-xen
    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

2.06% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 8.5 AV:N/AC:M/Au:S/C:C/I:C/A:C

Classification

Weakness

References

Sources

Fencer Intel 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.