Denial of service in Junos OS Evolved

Published: 2021-01-15
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2021-0209
Exploitation vector Network
Public exploit N/A
Vulnerable software
Junos OS Evolved
Operating systems & Components / Operating system


Security Advisory

This security advisory describes one medium risk vulnerability.

1) Access of Uninitialized Pointer

Risk: Medium

CVSSv3: 5.7 [CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C] [PCI]

CVE-ID: CVE-2021-0209

CWE-ID: CWE-824 - Access of Uninitialized Pointer

Exploit availability: No


The vulnerability allows a remote attacker to perform a DoS attack.

The vulnerability exists due to access to an uninitialized pointer in Regular expressions (REGEX) engine when processing valid BGP update packets from BGP peers. A remote attacker can certain valid BGP update packets and perform a denial of service (DoS) attack.


Install updates from vendor's website.

Juniper Networks Junos OS Evolved

  • 19.4 versions prior to 19.4R2-S2-EVO;
  • 20.1 versions prior to 20.1R1-S2-EVO, 20.1R2-S1-EVO.

Vulnerable software versions

Junos OS Evolved: before 19.4R2-S2-EVO, 20.1R1-S2-EVO, 20.1R2-S1-EVO, 20.2R1-EVO

CPE External links

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.