| Vulnerability Name: | CVE-2021-28689 (CCN-201170) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Assigned: | 2021-05-04 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Published: | 2021-05-04 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Updated: | 2021-06-24 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Summary: | 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. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| CVSS v3 Severity: | 5.5 Medium (CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N) 4.8 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C)
5.7 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C)
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| CVSS v2 Severity: | 2.1 Low (CVSS v2 Vector: AV:L/AC:L/Au:N/C:P/I:N/A:N)
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| Vulnerability Type: | CWE-119 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Vulnerability Consequences: | Obtain Information | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| References: | Source: MITRE Type: CNA CVE-2021-28689 Source: CCN Type: Xen Security Advisory XSA-370 x86: Speculative vulnerabilities with bare (non-shim) 32-bit PV guests Source: XF Type: UNKNOWN xen-cve202128689-info-disc(201170) Source: MISC Type: Vendor Advisory https://xenbits.xenproject.org/xsa/advisory-370.txt | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Vulnerable Configuration: | Configuration 1: Configuration CCN 1:  Denotes that component is vulnerable | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Oval Definitions | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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