Juniper Junos OS: Denial of service in rpd via BGP LLGR route updates
Summary
A remote BGP peer can crash the routing protocol daemon (rpd) of Junos OS and Junos OS Evolved by sending an LLGR-stale route update that is readvertised to a configured non-LLGR peer group. The attack requires that the BGP group has advertise-to-non-llgr-neighbor configured, more than 32 peers established in that group, and that update-threading is not configured. A successful attack crashes rpd and disrupts routing on the device.
Affected
- Junos OS: releases before 23.2R2-S7.7; 23.4 to before 23.4R2-S8.13; 24.2 to before 24.2R2-S5.5; 24.4 to before 24.4R2-S5; 25.2 to before 25.2R2-S2; 25.4 to before 25.4R1-S3; 26.2 to before 26.2R1-S2 (default: unaffected)
- Junos OS Evolved: releases before 23.2R2-S7.7-EVO; 23.4 to before 23.4R2-S8.11-EVO; 24.2 to before 24.2R2-S5.6-EVO; 24.4 to before 24.4R2-S5-EVO; 25.2 to before 25.2R2-S2-EVO; 25.4 to before 25.4R1-S3-EVO; 26.2 to before 26.2R1-S2-EVO; 23.4X100; 25.2X100 to before 25.2X100-D35-EVO; 25.4X300 to before 25.4X300-D40-EVO (default: 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, 25.4R1-S3-EVO, 25.4R2-EVO, 26.2R1-S2-EVO, 26.2R2-EVO, 26.4R1-EVO and all subsequent releases
Workaround
- Configure 'graceful-restart long-lived advertise-to-non-llgr-neighbor omit-no-export' or remove 'advertise-to-non-llgr-neighbor'.
Exploitation
- Juniper SIRT is not aware of any malicious exploitation.
- CISA SSVC: exploitation none, automatable yes, technical impact partial.
- Not listed in CISA KEV according to an aggregator.
Our recommendation
- Check whether Junos OS or Junos OS Evolved devices are in use, especially at the network edge.
- Apply the fixed releases listed in Juniper advisory JSA112187 and confirm the exact versions there.
- Until patching is possible, apply the workaround.
- Restrict BGP sessions to known peers and use session authentication and prefix filters.
- Monitor for unexpected rpd restarts and crash files.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Juniper Security Advisory JSA112187 supportportal.juniper.net
- VulnRichment CVE-2026-101957 (Vulners) vulners.com
- Strix CVE-2026-101957 www.strix.ai
- Offseq Radar CVE-2026-101957 radar.offseq.com
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, 03:53.
Original description (NVD)
An Improper Initialization vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a remote BGP peer to cause an rpd crash via an LLGR-stale route update readvertised to a configured non-LLGR peer group.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.