Junos OS and Junos OS Evolved: Local Privilege Escalation vulnerability

Description

A local privilege escalation vulnerability in Juniper Networks Junos OS and Junos OS Evolved allows a local, low-privileged user to cause the Juniper DHCP daemon (jdhcpd) process to crash, resulting in a Denial of Service (DoS), or execute arbitrary commands as root. Continued processing of malicious input will repeatedly crash the system and sustain the Denial of Service (DoS) condition. Systems are only vulnerable if jdhcpd is running, which can be confirmed via the 'show system processes' command. For example: root@host# run show system processes extensive | match dhcp 26537 root -16 0 97568K 13692K RUN 0 0:01 3.71% jdhcpd This issue affects: Juniper Networks Junos OS: All versions, including the following supported releases: 15.1 versions prior to 15.1R7-S10; 17.4 versions prior to 17.4R3-S5; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R3-S9; 19.1 versions prior to 19.1R3-S6; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S6, 19.3R3-S3; 19.4 versions prior to 19.4R3-S6; 20.1 versions prior to 20.1R2-S2, 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R2-S1, 20.4R3; 21.1 versions prior to 21.1R1-S1, 21.1R2. Juniper Networks Junos OS Evolved: All versions prior to 20.4R2-S3-EVO; All versions of 21.1-EVO.

Timeline

Scores

EPSS (exploitation in 30 days)

0.24% · top 84% of all CVEs (7 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Weakness

• CWE-269 Improper Privilege Management (opens in a new tab)All about CWE-269 and its CVEs
• CWE-121 Stack-based Buffer Overflow (opens in a new tab)All about CWE-121 and its CVEs
• Denial of Service (DoS)

Affected products

• Juniper Networks · Junos OS

  • affected 15.1 – < 15.1R7-S10
  • affected 17.4 – < 17.4R3-S5
  • affected 18.3 – < 18.3R3-S5
  • affected 18.4 – < 18.4R3-S9
  • affected 19.1 – < 19.1R3-S6
  • affected 19.2 – < 19.2R1-S7, 19.2R3-S3
  • affected 19.3 – < 19.3R2-S6, 19.3R3-S3
  • affected 19.4 – < 19.4R3-S6
  • affected 20.1 – < 20.1R2-S2, 20.1R3-S1
  • affected 20.2 – < 20.2R3-S2
  • affected 20.3 – < 20.3R3
  • affected 20.4 – < 20.4R2-S1, 20.4R3
  • affected 21.1 – < 21.1R1-S1, 21.1R2

• Juniper Networks · Junos OS Evolved

  • affected unspecified – < 20.4R2-S3-EVO
  • affected 21.1R1-EVO – < 21.1*

What to do

Solution: The following software releases have been updated to resolve this specific issue: Junos OS 15.1R7-S10, 17.4R3-S5, 18.3R3-S5, 18.4R3-S9, 19.1R3-S6, 19.2R1-S7, 19.2R3-S3, 19.3R2-S6, 19.3R3-S3, 19.4R3-S6, 20.1R2-S2, 20.1R3-S1, 20.2R3-S2, 20.3R3, 20.4R2-S1, 20.4R3, 21.1R1-S1, 21.1R2, 21.1R3, 21.2R1, and all subsequent releases. Junos OS Evolved 20.4R2-S3-EVO, 21.2R1-EVO, and all subsequent releases.

Workaround: Use access lists or firewall filters to limit access to the device via CLI only from trusted hosts and from trusted administrators.

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

References (1)

• https://kb.juniper.net/JSA11222 (opens in a new tab)x_refsource_CONFIRMx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2021-31359](https://trackcve.app/badge/CVE-2021-31359.svg)](https://trackcve.app/cve/CVE-2021-31359)

Record last updated 16 Sept 2024, 23:55 UTC.