CVE-2021-28703

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.

7.0

CVSS

Severity: High

CVSS 3.1 •

CVSS 2.0 •

EPSS 0.11%

Vendor Advisory gentoo.org Vendor Advisory xenproject.org

Affected: Xen Project Xen

References

Link	Tags
https://xenbits.xenproject.org/xsa/advisory-387.txt	vendor advisory
https://security.gentoo.org/glsa/202402-07	vendor advisory

Frequently Asked Questions

What is the severity of CVE-2021-28703?: CVE-2021-28703 has been scored as a high severity vulnerability.
How to fix CVE-2021-28703?: To fix CVE-2021-28703, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-28703 being actively exploited in the wild?: As for now, there are no information to confirm that CVE-2021-28703 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-28703?: CVE-2021-28703 affects Xen Project Xen.

This platform uses data from the NIST NVD, MITRE CVE, MITRE CWE, First.org and CISA KEV but is not endorsed or certified by these entities. CVE is a registred trademark of the MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. CWE is a registred trademark of the MITRE Corporation and the authoritative source of CWE content is MITRE's CWE web site.