CVE-2018-12891

unknown

Published — · Modified —

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CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

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Description

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.

Predictions

Exploit likelihood

20%

Patch ETA

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Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

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OS impact

SUSE Affected 1 release

Version	Status	Fixed in
—	Affected	—

Debian Fixed 5 releases

Version	Status	Fixed in
trixie	Fixed	`4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9`
sid	Fixed	`4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9`
forky	Fixed	`4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9`
bullseye	Fixed	`4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9`
bookworm	Fixed	`4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9`

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

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