CVE-2021-28703 (GCVE-0-2021-28703)

Vulnerability from cvelistv5 – Published: 2021-12-07 00:00 – Updated: 2024-08-03 21:47
VLAI?
Summary
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.
Severity ?
No CVSS data available.
CWE
  • unknown
Assigner
XEN
References
Impacted products
Vendor Product Version
Xen Project Xen Unaffected: Branch 4.13.4 4.13.4
Unaffected: Branch 4.14.x 4.14.x
Unaffected: Branch 4.15.x 4.15.x
Affected: Branch 4.13 , ≤ 4.13 (custom)
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Credits
{'credit_data': {'description': {'description_data': [{'lang': 'eng', 'value': 'This issue was discovered by Patryk Balicki and Julien Grall of Amazon.'}]}}}
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  }
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.