CVE-2022-42332: x86 shadow plus log-dirty mode use-after-free In environments where host assisted address translation is necessary but Hardware Assisted Paging (HAP) ...

Description

x86 shadow plus log-dirty mode use-after-free In environments where host assisted address translation is necessary but Hardware Assisted Paging (HAP) is unavailable, Xen will run guests in so called shadow mode. Shadow mode maintains a pool of memory used for both shadow page tables as well as auxiliary data structures. To migrate or snapshot guests, Xen additionally runs them in so called log-dirty mode. The data structures needed by the log-dirty tracking are part of aformentioned auxiliary data. In order to keep error handling efforts within reasonable bounds, for operations which may require memory allocations shadow mode logic ensures up front that enough memory is available for the worst case requirements. Unfortunately, while page table memory is properly accounted for on the code path requiring the potential establishing of new shadows, demands by the log-dirty infrastructure were not taken into consideration. As a result, just established shadow page tables could be freed again immediately, while other code is still accessing them on the assumption that they would remain allocated.

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.27%

18.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-416

Affected Software

Vendor	Product	Versions
Xen	Xen	>= 3.2.0
Debian	Debian Linux	11.0
Fedoraproject	Fedora	37
Fedoraproject	Fedora	38

References

http://www.openwall.com/lists/oss-security/2023/03/21/1Mailing List, Third Party Advisory
http://xenbits.xen.org/xsa/advisory-427.htmlVendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5L6PM4RE7MUE6OWA32ZVOXCP235RM2TM/Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APBMS2Q6746AXAFAITNJMGBNFGNMVLWR/Mailing List, Third Party Advisory
https://security.gentoo.org/glsa/202402-07
https://www.debian.org/security/2023/dsa-5378Third Party Advisory
https://xenbits.xenproject.org/xsa/advisory-427.txtVendor Advisory
http://www.openwall.com/lists/oss-security/2023/03/21/1Mailing List, Third Party Advisory
http://xenbits.xen.org/xsa/advisory-427.htmlVendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5L6PM4RE7MUE6OWA32ZVOXCP235RM2TM/Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APBMS2Q6746AXAFAITNJMGBNFGNMVLWR/Mailing List, Third Party Advisory
https://security.gentoo.org/glsa/202402-07
https://www.debian.org/security/2023/dsa-5378Third Party Advisory
https://xenbits.xenproject.org/xsa/advisory-427.txtVendor Advisory

Timeline

Published: Mar 21, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2022-42332?

x86 shadow plus log-dirty mode use-after-free In environments where host assisted address translation is necessary but Hardware Assisted Paging (HAP) is unavailable, Xen will run guests in so called shadow mode. Shadow mode maintains a pool of memory used for both shadow page tables as well as auxiliary data structures. To migrate or snapshot guests, Xen additionally runs them in so called log-dirty mode. The data structures needed by the log-dirty tracking are part of aformentioned auxiliary data. In order to keep error handling efforts within reasonable bounds, for operations which may require memory allocations shadow mode logic ensures up front that enough memory is available for the worst case requirements. Unfortunately, while page table memory is properly accounted for on the code path requiring the potential establishing of new shadows, demands by the log-dirty infrastructure were not taken into consideration. As a result, just established shadow page tables could be freed again immediately, while other code is still accessing them on the assumption that they would remain allocated.

How severe is CVE-2022-42332?

CVE-2022-42332 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.

How do I fix CVE-2022-42332?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.