CVE-2018-12891
xen - security update
描述
An issue was discovered in Xen through 4.10.x. Certain PV MMU operations may take a long time to process. For that reason Xen explicitly checks for the need to preempt the current vCPU at certain points. A few rarely taken code paths did bypass such checks. By suitably enforcing the conditions through its own page table contents, a malicious guest may cause such bypasses to be used for an unbounded number of iterations. A malicious or buggy PV guest may cause a Denial of Service (DoS) affecting the entire host. Specifically, it may prevent use of a physical CPU for an indeterminate period of time. All Xen versions from 3.4 onwards are vulnerable. Xen versions 3.3 and earlier are vulnerable to an even wider class of attacks, due to them lacking preemption checks altogether in the affected code paths. Only x86 systems are affected. ARM systems are not affected. Only multi-vCPU x86 PV guests can leverage the vulnerability. x86 HVM or PVH guests as well as x86 single-vCPU PV ones cannot leverage the vulnerability.
如何修補 CVE-2018-12891
要修補 CVE-2018-12891,請將受影響套件升級到下列已修補版本。
- —升級至 4.11.0-r0 或更新版本
- —升級至 4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9 或更新版本
- —升級至 4.4.4lts4-0+deb8u1 或更新版本
- —升級至 4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9 或更新版本
CVE-2018-12891 正在被利用嗎?
低 — EPSS 為 0.4%,目前沒有觀察到大規模利用活動。
受影響套件(4)
- from 0, < 4.11.0-r0
- from 0, < 4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9
- from 0, < 4.4.4lts4-0+deb8u1
- from 0, < 4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9
CVSS 分數
| 來源 | 版本 | 嚴重程度 | 向量 |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.5 | CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H |