5.5
MEDIUM
CVE-2021-28687
Libxl Uninitialized Structure Crash Vulnerability in Xen Toolstack
Description

HVM soft-reset crashes toolstack libxl requires all data structures passed across its public interface to be initialized before use and disposed of afterwards by calling a specific set of functions. Many internal data structures also require this initialize / dispose discipline, but not all of them. When the "soft reset" feature was implemented, the libxl__domain_suspend_state structure didn't require any initialization or disposal. At some point later, an initialization function was introduced for the structure; but the "soft reset" path wasn't refactored to call the initialization function. When a guest nwo initiates a "soft reboot", uninitialized data structure leads to an assert() when later code finds the structure in an unexpected state. The effect of this is to crash the process monitoring the guest. How this affects the system depends on the structure of the toolstack. For xl, this will have no security-relevant effect: every VM has its own independent monitoring process, which contains no state. The domain in question will hang in a crashed state, but can be destroyed by `xl destroy` just like any other non-cooperating domain. For daemon-based toolstacks linked against libxl, such as libvirt, this will crash the toolstack, losing the state of any in-progress operations (localized DoS), and preventing further administrator operations unless the daemon is configured to restart automatically (system-wide DoS). If crashes "leak" resources, then repeated crashes could use up resources, also causing a system-wide DoS.

INFO

Published Date :

June 11, 2021, 3:15 p.m.

Last Modified :

Sept. 20, 2021, 1:51 p.m.

Remotely Exploitable :

No

Impact Score :

3.6

Exploitability Score :

1.8
Affected Products

The following products are affected by CVE-2021-28687 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Xen xen
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-28687.

URL Resource
https://security.gentoo.org/glsa/202107-30 Third Party Advisory
https://xenbits.xenproject.org/xsa/advisory-368.txt Vendor Advisory

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-28687 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2021-28687 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • Modified Analysis by [email protected]

    Sep. 20, 2021

    Action Type Old Value New Value
    Changed Reference Type https://security.gentoo.org/glsa/202107-30 No Types Assigned https://security.gentoo.org/glsa/202107-30 Third Party Advisory
    Changed CPE Configuration OR *cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:* versions from (including) 4.12 up to (including) 4.14 OR *cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:* versions from (including) 4.12 up to (including) 4.15.0 *cpe:2.3:o:xen:xen:4.15.0:rc1:*:*:*:*:*:*
  • CVE Modified by [email protected]

    Jul. 12, 2021

    Action Type Old Value New Value
    Added Reference https://security.gentoo.org/glsa/202107-30 [No Types Assigned]
  • Initial Analysis by [email protected]

    Jun. 24, 2021

    Action Type Old Value New Value
    Added CVSS V2 NIST (AV:L/AC:L/Au:N/C:N/I:N/A:C)
    Added CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
    Changed Reference Type https://xenbits.xenproject.org/xsa/advisory-368.txt No Types Assigned https://xenbits.xenproject.org/xsa/advisory-368.txt Vendor Advisory
    Added CWE NIST CWE-909
    Added CPE Configuration OR *cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:* versions from (including) 4.12 up to (including) 4.14
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-28687 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-28687 weaknesses.

Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

0.04 }} 0.00%

score

0.10264

percentile

CVSS31 - Vulnerability Scoring System
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