High · CVSS 8.7CVE-2026-101951

Junos OS and Junos OS Evolved: A BGP peer causes an rpd crash if a malformed MCAST-TREE NLRI is received and readvertisedCVE-2026-101951

Answer in brief

CVE-2026-101951 records a High severity (CVSS 8.7) vulnerability in Junos OS and Junos OS Evolved: A BGP peer causes an rpd crash if a malformed MCAST-TREE NLRI is received and readvertised. The current sources do not mark it as known exploited. The current feed maps Juniper Networks/Junos OS (generic), Juniper Networks/Junos OS Evolved (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 14, 2026Updated Oct 14, 2026Source checked Oct 14, 2026First seen by HOL Oct 14, 2026Material review Oct 14, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.7
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 8.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Juniper Networks/Junos OS (generic), Juniper Networks/Junos OS Evolved (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Juniper Networks/Junos OSgeneric	>=0 <23.2R2-S7.7 \|\| >=23.4 <23.4R2-S8.13 \|\| >=24.2 <24.2R2-S5.5 \|\| >=24.4 <24.4R2-S5 \|\| >=25.2 <25.2R2-S2 \|\| >=25.4 <25.4R1-S3 \|\| >=26.2 <26.2R1-S2	23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 26.2R1-S2
Juniper Networks/Junos OS Evolvedgeneric	>=0 <23.2R2-S7.7-EVO \|\| >=23.4 <23.4R2-S8.11-EVO \|\| >=24.2 <24.2R2-S5.6-EVO \|\| >=24.4 <24.4R2-S5-EVO \|\| >=25.2 <25.2R2-S2-EVO \|\| >=25.4 <25.4R1-S3-EVO \|\| >=26.2 <26.2R1-S2-EVO \|\| 23.4X100 \|\| >=25.2X100 <25.2X100-D35-EVO \|\| >=25.4X300 <25.4X300-D40-EVO	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, 26.2R1-S2-EVO, 25.2X100-D35-EVO, 25.4X300-D40-EVO

Recommended response

Check inventory. Check lockfiles and deployed manifests for Juniper Networks/Junos OS, Juniper Networks/Junos OS Evolved.
Review the reported fix. Source-reported solution: The following software releases have been updated to resolve this specific issue: 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. Note: For Junos OS releases 23.2, 23.4, and 24.2, and Junos OS Evolved releases 23.2-EVO, 23.4-EVO, and 24.2-EVO, specific respins have been referenced. Previously published versions of these releases have been rebuilt to resolve the security vulnerabilities identified in this advisory.

Evidence timeline and material changes

Published upstream
Oct 14, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 14, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 14, 2026

Sources and claim methodology

Source referencesupportportal.juniper.net

Upstream source description

An Improper Validation of Consistency within Input vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-adjacent configured BGP peer to cause a denial of service by sending a specifically malformed BGP MCAST-TREE update and this NLRI is then attempted to be readvertised.

Quoted source text, attributed separately from HOL analysis.