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Junos OS: Stack-based buffer overflow in authd allows code execution via SNMP

CVE-2026-101979High 8.7

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Summary

A stack-based buffer overflow in the authd daemon of Junos OS and Junos OS Evolved affects Juniper routers, switches and security devices. A network attacker with SNMP read access can send a specific SNMP packet to execute code with root privileges or to cause a denial of service. The attack requires SNMP and AAA to be enabled on the device.

Affected

  • Junos OS: earlier than 23.2R2-S7.7, 23.4 before 23.4R2-S8.13, 24.2 before 24.2R2-S5.5, 24.4 before 24.4R2-S5, 25.2 before 25.2R2-S2, 25.4 before 25.4R1-S3, 26.2 before 26.2R1-S2
  • Junos OS Evolved: earlier than 23.2R2-S7.7-EVO, 23.4 before 23.4R2-S8.11-EVO, 24.2 before 24.2R2-S5.6-EVO, 24.4 before 24.4R2-S5-EVO, 25.2 before 25.2R2-S2-EVO, 25.4 before 25.4R1-S3-EVO, 26.2 before 26.2R1-S2-EVO
  • Unknown: 23.4X100 (Evolved) is listed as affected without a fixed release; confirm in the advisory

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 later
  • 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 later
  • Previously published releases of 23.2, 23.4 and 24.2 have been rebuilt (respins); check JSA112187 for exact build IDs

Workaround

  • No known workarounds according to the CVE record; the vendor advisory should be checked
  • Unverified practical mitigation: restrict SNMP access to trusted management hosts, limit the read-only community to trusted hosts or use SNMPv3 with restricted users, and do not expose SNMP to untrusted networks

Exploitation

  • Juniper SIRT is not aware of any malicious exploitation
  • CISA SSVC: Exploitation none, Automatable no, Technical Impact total
  • No public proof of concept or in-the-wild exploitation found in the research notes; not checked against CISA KEV

Our recommendation

  • Inventory all Junos OS and Junos OS Evolved devices and their versions
  • Check whether SNMP and AAA are enabled and which hosts can reach SNMP
  • Restrict SNMP access to trusted management networks now
  • Plan upgrades to the fixed releases listed in JSA112187 after confirming exact versions in the advisory
  • Monitor SNMP and authentication logs for unusual requests

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, 02:52.

Original description (NVD)

A Stack-based Buffer Overflow vulnerability in the authd Juniper Networks Junos OS and Junos OS Evolved allows a network attacker with SNMP read access to execute code with root privileges or cause a denial of service via a specific SNMP packet, when SNMP and AAA are enabled.

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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