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2019-04 Security Bulletin: SRX Series: A remote attacker may cause a high CPU Denial of Service to the device when proxy ARP is configured. (CVE-2019-0033)

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Product Affected:
This issue affects Junos OS 12.1X46, 12.3X48, 15.1X49. Affected platforms: SRX Series.

A firewall bypass vulnerability in the proxy ARP service of Juniper Networks Junos OS allows an attacker to cause a high CPU condition leading to a Denial of Service (DoS).

This issue affects only IPv4.

Affected releases are Juniper Networks Junos OS:

  • 12.1X46 versions above and including 12.1X46-D25 prior to 12.1X46-D71, 12.1X46-D73 on SRX Series;
  • 12.3X48 versions prior to 12.3X48-D50 on SRX Series;
  • 15.1X49 versions prior to 15.1X49-D75 on SRX Series.

An example configuration snippet is below:

root@device# show security nat proxy-arp
interface ge-0/0/0.0 {
  address {;

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

This issue has been assigned CVE-2019-0033.

The following software releases have been updated to resolve this specific issue: 12.1X46-D71, 12.1X46-D73, 12.3X48-D50, 15.1X49-D75, 17.3R1, and all subsequent releases.

Please refer to KB21785 for further information related to configuring Proxy ARP services.

This issue is being tracked as PR 1208910 which is visible on the Customer Support website.

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

Discontinue use of proxy ARP.

An example configuration snippet is below:

deactivate security nat proxy-arp interface ge-0/0/0.0 address


delete security nat proxy-arp interface ge-0/0/0.0 address

There are no other viable workarounds for this issue.

Software Releases, patches and updates are available at
Modification History:
  • 2019-04-10: Initial Publication.
  • ‚Äč2019-06-14: Added reference information for configuring Proxy ARP services to Solution section and to Related Links for
Related Links:
CVSS Score:
7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."