CVE-2021-28701

Another race in XENMAPSPACE_grant_table handling Guests are 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, are de-allocated when a guest switches (back) from v2 to v1. Freeing such pages requires that the hypervisor enforce that no parallel request can result in the addition of a mapping of such a page to a guest. That enforcement was missing, allowing guests to retain access to pages that were freed and perhaps re-used for other purposes. Unfortunately, when XSA-379 was being prepared, this similar issue was not noticed.

• CWE-362

• http://www.openwall.com/lists/oss-security/2021/09/08/2Mailing List, Third Party Advisory
• http://xenbits.xen.org/xsa/advisory-384.htmlVendor Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3HEHUIUWSSMCQGQY3GWX4J2SZGYP5W2Z/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEHZLIR5DFYYQBH55AERWHLO54OFU42C/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L4MI3MQAPGILCLXBGQWPZHGE3ALSO4ZU/
• https://security.gentoo.org/glsa/202208-23Third Party Advisory
• https://www.debian.org/security/2021/dsa-4977Third Party Advisory
• https://xenbits.xenproject.org/xsa/advisory-384.txtVendor Advisory
• http://www.openwall.com/lists/oss-security/2021/09/08/2Mailing List, Third Party Advisory
• http://xenbits.xen.org/xsa/advisory-384.htmlVendor Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3HEHUIUWSSMCQGQY3GWX4J2SZGYP5W2Z/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEHZLIR5DFYYQBH55AERWHLO54OFU42C/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L4MI3MQAPGILCLXBGQWPZHGE3ALSO4ZU/
• https://security.gentoo.org/glsa/202208-23Third Party Advisory
• https://www.debian.org/security/2021/dsa-4977Third Party Advisory
• https://xenbits.xenproject.org/xsa/advisory-384.txtVendor Advisory

Published

Sep 8, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2021-28695IOMMU page mapping issues on x86 T[his CNA information recor…6.8
• CVE-2021-28696IOMMU page mapping issues on x86 T[his CNA information recor…6.8
• CVE-2021-28697grant table v2 status pages may remain accessible after de-a…7.8
• CVE-2021-28698long running loops in grant table handling In order to prope…5.5
• CVE-2021-28699inadequate grant-v2 status frames array bounds check The v2 …5.5
• CVE-2021-28700xen/arm: No memory limit for dom0less domUs The dom0less fea…4.9
• CVE-2021-28702PCI devices with RMRRs not deassigned correctly Certain PCI …7.6
• CVE-2021-28703grant table v2 status pages may remain accessible after de-a…7
• CVE-2021-28704PoD operations on misaligned GFNs T[his CNA information reco…8.8
• CVE-2021-28705issues with partially successful P2M updates on x86 T[his CN…7.8
• CVE-2021-28706guests may exceed their designated memory limit When a guest…8.6
• CVE-2021-28707PoD operations on misaligned GFNs T[his CNA information reco…8.8