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CVE-2020-11739
CVE ID
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CVE-2020-11739
MITRE ATT&CK
Collection
Command and Control
Credential Access
Defense Evasion
Discovery
Execution
Exfiltration
Impact
Initial Access
Lateral Movement
Persistence
Privilege Escalation
Topic Tags
Description
An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service or possibly gain privileges because of missing memory barriers in read-write unlock paths. The read-write unlock paths don’t contain a memory barrier. On Arm, this means a processor is allowed to re-order the memory access with the preceding ones. In other words, the unlock may be seen by another processor before all the memory accesses within the “critical” section. As a consequence, it may be possible to have a writer executing a critical section at the same time as readers or another writer. In other words, many of the assumptions (e.g., a variable cannot be modified after a check) in the critical sections are not safe anymore. The read-write locks are used in hypercalls (such as grant-table ones), so a malicious guest could exploit the race. For instance, there is a small window where Xen can leak memory if XENMAPSPACE_grant_table is used concurrently. A malicious guest may be able to leak memory, or cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded.
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CVSS V3 Severity and Metrics
General Information
Vendors
- debian,
- fedoraproject,
- opensuse,
- xen
Products
- debian linux 10.0,
- fedora 30,
- fedora 31,
- fedora 32,
- leap 15.1,
- xen,
- xen 4.13.0
References
Advisory
Miscellaneous
Additional Info
Technical Analysis
Report as Exploited in the Wild
CVE ID
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