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NULL Pointer Dereference The advisory has been revoked - it doesn't affect any version of package xen  (opens in a new tab)

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EPSS
0.39% (31st percentile)

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  • Snyk IDSNYK-UBUNTU1604-XEN-1052945
  • published19 Dec 2020
  • disclosed15 Dec 2020
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Introduced: 15 Dec 2020

CVE-2020-29571  (opens in a new tab)
CWE-476  (opens in a new tab)

Amendment

The Ubuntu security team deemed this advisory irrelevant for Ubuntu:16.04.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xen package and not the xen package as distributed by Ubuntu.

An issue was discovered in Xen through 4.14.x. A bounds check common to most operation time functions specific to FIFO event channels depends on the CPU observing consistent state. While the producer side uses appropriately ordered writes, the consumer side isn't protected against re-ordered reads, and may hence end up de-referencing a NULL pointer. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. Only Arm systems may be vulnerable. Whether a system is vulnerable depends on the specific CPU. x86 systems are not vulnerable.