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CVE-2021-28689

Quick assessment

Affected
Xen Xen
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Xen是英国剑桥（Cambridge）大学的一款开源的虚拟机监视器产品。该产品能够使不同和不兼容的操作系统运行在同一台计算机上，并支持在运行时进行迁移，保证正常运行并且避免宕机。 Xen 的 Bare 32-bit PV Guests 存在安全漏洞，攻击者可利用该漏洞绕过对数据的访问限制，以获取主机系统上的敏感信息。

AI Predicted 5.6 Difficulty: Moderate EPSS 0.36% · P29

Possible ATT&CK Techniques 2 AI

T1042 T1608 · Stage Capabilities
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I. Basic Information for CVE-2021-28689

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability Description
x86: Speculative vulnerabilities with bare (non-shim) 32-bit PV guests 32-bit x86 PV guest kernels run in ring 1. At the time when Xen was developed, this area of the i386 architecture was rarely used, which is why Xen was able to use it to implement paravirtualisation, Xen's novel approach to virtualization. In AMD64, Xen had to use a different implementation approach, so Xen does not use ring 1 to support 64-bit guests. With the focus now being on 64-bit systems, and the availability of explicit hardware support for virtualization, fixing speculation issues in ring 1 is not a priority for processor companies. Indirect Branch Restricted Speculation (IBRS) is an architectural x86 extension put together to combat speculative execution sidechannel attacks, including Spectre v2. It was retrofitted in microcode to existing CPUs. For more details on Spectre v2, see: http://xenbits.xen.org/xsa/advisory-254.html However, IBRS does not architecturally protect ring 0 from predictions learnt in ring 1. For more details, see: https://software.intel.com/security-software-guidance/deep-dives/deep-dive-indirect-branch-restricted-speculation Similar situations may exist with other mitigations for other kinds of speculative execution attacks. The situation is quite likely to be similar for speculative execution attacks which have yet to be discovered, disclosed, or mitigated.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Cambridge Xen 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Xen是英国剑桥（Cambridge）大学的一款开源的虚拟机监视器产品。该产品能够使不同和不兼容的操作系统运行在同一台计算机上，并支持在运行时进行迁移，保证正常运行并且避免宕机。 Xen 的 Bare 32-bit PV Guests 存在安全漏洞，攻击者可利用该漏洞绕过对数据的访问限制，以获取主机系统上的敏感信息。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Xen Xen unspecified ~ 4.12 -

II. Public POCs for CVE-2021-28689

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III. Intelligence Information for CVE-2021-28689

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Other References for CVE-2021-28689 (1)

IV. Related Vulnerabilities

Same product: Xen
Same vendor: Xen

V. Comments for CVE-2021-28689

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