7

CVE-2021-28703: xen project xen

Modified
AliasesALPINE-CVE-2021-28703UBUNTU-CVE-2021-28703DEBIAN-CVE-2021-28703
Published 07-12-2021Last modified 03-08-2024

Vulnerability summary

CVE-2021-28703 is a high (CVSS 7.0) vulnerability in xen project xen. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.6% of scored vulnerabilities.

Overall risk
28/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.0/10
010
High · v3.1 (NVD)
EPSS score
0.33%
0%100%
Low · +0.02 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
SUSE-SU-2021:14848-1

Timeline

  1. 07-12-2021
    PublishedVulnerability first disclosed.
  2. 03-08-2024
    Last modifiedVulnerability information updated.

Description

grant table v2 status pages may remain accessible after de-allocation (take two) Guest get permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, get de-allocated when a guest switched (back) from v2 to v1. The freeing of such pages requires that the hypervisor know where in the guest these pages were mapped. The hypervisor tracks only one use within guest space, but racing requests from the guest to insert mappings of these pages may result in any of them to become mapped in multiple locations. Upon switching back from v2 to v1, the guest would then retain access to a page that was freed and perhaps re-used for other purposes. This bug was fortuitously fixed by code cleanup in Xen 4.14, and backported to security-supported Xen branches as a prerequisite of the fix for XSA-378.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.33%

Chance of exploitation in the next 30 days

Percentile

25%

Versus all other CVEs

30-day change

Increase +0.02 pp

From 0.31% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Alpine1 product
  • xen< 4.13.4-r0 | < 4.14.5-r0 | < 4.15.2-r0 | < 4.15.1-r1
Debian1 product
  • xen< 4.14.0+80-gd101b417b7-1
Ubuntu1 product
  • xenAll versions (No fix recorded)
Xen1 product
Xen project1 product
  • xen≥ Branch 4.13, ≤ 4.13

5 vendors · 5 products

References

7 links