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Junos OS: OS command injection in phone-home daemon phcd

CVE-2026-102059High 8.7

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Summary

The phone-home daemon (phcd) in Junos OS and Junos OS Evolved on EX Series, SRX Series and QFX Series devices contains an OS command injection flaw. An adjacent, unauthenticated attacker can send crafted input from a rogue DHCP server and execute arbitrary commands with root privileges. No user interaction is required, and the attack is most relevant during device onboarding when DHCP and phone-home are active.

Affected

  • Junos OS: below 23.2R2-S7.7; 23.4 to below 23.4R2-S8.13; 24.2 to below 24.2R2-S5.5; 24.4 to below 24.4R2-S5; 25.2 to below 25.2R2-S2; 25.4 to below 25.4R1-S3; 26.2 to below 26.2R1-S2 (default configuration unaffected)
  • Junos OS Evolved: below 23.2R2-S7.7-EVO; 23.4 to below 23.4R2-S8.11-EVO; 24.2 to below 24.2R2-S5.6-EVO; 24.4 to below 24.4R2-S5-EVO; 25.2 to below 25.2R2-S2-EVO; 25.4 to below 25.4R1-S3-EVO; 26.2 to below 26.2R1-S2-EVO; 23.4X100 and 25.4X300 ranges as listed in the CNA record (default configuration unaffected)

Fixed in

  • Junos OS: 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 25.4R2, 26.2R1-S2, 26.2R2, 26.4R1 and all subsequent releases
  • Junos OS Evolved: 23.2R2-S7.7-EVO, 23.4R2-S8.11-EVO, 24.2R2-S5.6-EVO, 24.4R2-S5-EVO, 25.2R2-S2-EVO, 25.2X100-D35-EVO, 25.4R1-S3-EVO, 25.4R2-EVO, 25.4X300-D40-EVO, 26.2R1-S2-EVO, 26.2R2-EVO, 26.4R1-EVO and all subsequent releases
  • Releases 23.2, 23.4 and 24.2 (and their EVO equivalents) have respins; previously published builds were rebuilt. Exact fix build per train to be verified in JSA112187.

Workaround

Unknown. The CNA record states there are no known workarounds. Upgrading is the only fix.

Exploitation

  • Juniper SIRT is not aware of any malicious exploitation.
  • Not listed in CISA's Known Exploited Vulnerabilities catalog.
  • CISA SSVC: exploitation none, automatable no, technical impact total.
  • No public proof of concept found.

Our recommendation

  • Inventory all EX, SRX and QFX devices and their Junos OS or Junos OS Evolved versions.
  • Upgrade to a fixed release as listed in JSA112187, and patch CVE-2026-102061 (same daemon, same advisory) at the same time.
  • Until patched, limit DHCP and phone-home exposure to trusted VLANs and ports, and restrict who can reach the device segment.
  • Monitor for unexpected root processes or configuration changes on network devices.
  • Verify the advisory text and the "23.4X100" entry before rollout, because the exact fixed builds could not be fully confirmed.

Public exploits

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 03:11.

Original description (NVD)

An Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in the phone-home daemon (phcd) of Juniper Networks Junos OS and Junos OS Evolved on EX Series, SRX Series, and QFX Series allows an adjacent unauthenticated attacker to execute arbitrary commands with root privileges via a rogue DHCP server.

NVD references (1)

Sources

The tracker combines official, freely usable data sources – updated continuously:

This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.

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