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Junos OS CVE-2026-101988

| EUVDEUVD-2026-101482 HIGH
NULL Pointer Dereference (CWE-476)
2026-10-14 juniper GHSA-mhg9-x642-cgj6
7.1
CVSS 4.0 · Vendor: juniper
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Gain adjacent LDP peer position
  2. Delivery
    Establish operational LDP session
  3. Exploit
    Send crafted LDP message
  4. Execution
    Trigger NULL dereference in rpd
  5. Impact
    Crash routing daemon (DoS)

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Null pointer safety, defensive checks
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires MPLS with LDP configured and running on the target, and an already-operational LDP session with the victim - the attacker must be an established/adjacent LDP peer, so this is not exploitable against default (non-MPLS/non-LDP) configurations. Exploitation is unauthenticated (PR:N) but constrained to the adjacent network position (AV:A), meaning the attacker must sit on the same routing segment or be an accepted LDP neighbor rather than attack over the open Internet. Limiting factors: LDP feature must be enabled, a live LDP session must exist, and attacker must have adjacency - these materially reduce the realistic exposed population despite the unauthenticated vector.

Impact

This is a moderate-severity, single-impact (availability-only) denial-of-service flaw. The vendor CVSS 4.0 vector (AV:A/AC:L/AT:N/PR:N/UI:N) and the description agree internally: exploitation is adjacent (not routable Internet-wide), unauthenticated, and low-complexity, with VA:H plus SA:L capturing the crash of the routing daemon and resulting loss of routed traffic. There is no CVSS 3.1 vector in the input, no EPSS probability, no KEV listing, and no POC - so every exploitation-likelihood signal beyond CVSS is simply absent rather than conflicting. The practical gating factor is the requirement for an 'operational LDP session': the attacker must already be an established or adjacent LDP peer, which substantially narrows the attacker population versus a raw AV:A reading and makes untargeted mass exploitation unlikely. Net: a real but bounded priority - patch on MPLS/LDP-enabled routers, especially in carrier/ISP cores, but it is not a drop-everything Internet-exposed RCE. No availability of EPSS/KEV/POC data means exploitation likelihood cannot be quantified from the provided sources.

Exploit ScenarioDerived

An attacker positioned as an adjacent LDP peer (or on the same L2 segment able to participate in LDP) sends a malformed LDP message over an already-operational LDP session to a Junos OS or Junos OS Evolved device. The message triggers a NULL pointer dereference in the routing protocol daemon (rpd), crashing it and disrupting MPLS label distribution and routing on the target. No public exploit identified at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv3 – Oct 14, 2026

Denial of service in Juniper Networks Junos OS and Junos OS Evolved occurs when an unauthenticated adjacent attacker who is an established LDP peer sends crafted LDP messages, triggering a NULL pointer dereference in the routing protocol daemon (rpd) that can crash the daemon. The flaw is availability-only (CVSS 3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and requires MPLS with LDP configured and an operational LDP session; default configurations without MPLS/LDP are not exploitable. No public exploit was identified at time of analysis and the issue is not listed in CISA KEV.

Earlier versions of this analysis (2)
v2 Oct 14, 2026 - 17:58 cvss changed CVSS 7.1

Crafted LDP messages sent over an operational LDP session to Juniper Networks Junos OS or Junos OS Evolved can trigger a NULL pointer dereference in the routing protocol daemon (rpd), leading to a denial of service. The attacker must be on an adjacent network and no authentication is required, but exploitation is limited to deployments where MPLS with LDP is configured and an LDP session is established with the attacker's adjacent device. No public exploit code or active exploitation has been identified at time of analysis, and the real-world risk is tightly bounded by these preconditions.

v1 Oct 14, 2026 - 17:08 CVSS 6.5

Denial of service in Juniper Junos OS and Junos OS Evolved occurs when the routing protocol daemon (rpd) dereferences a NULL pointer while processing crafted LDP messages received over an already-established LDP session, crashing the daemon and disrupting routing. The flaw is remotely triggerable by an adjacent (AV:A), unauthenticated (PR:N) attacker but only on devices where LDP/MPLS is configured and an operational LDP peering relationship exists; non-LDP deployments are effectively unaffected, and impact is limited to availability (CVSS 6.5, C:N/I:N/A:H). No public exploit code or confirmed active exploitation was identified at time of analysis, so risk should be prioritized by actual LDP/MPLS exposure rather than the base score alone.

RemediationAI

Apply the patched Junos OS or Junos OS Evolved release specified in Juniper advisory JSA112187 (https://supportportal.juniper.net/JSA112187); no fixed version is provided in the available data, so consult the advisory for exact patched releases. If patching is not immediately possible, disable LDP or MPLS if those features are not required-this removes the attack surface but will break MPLS-based services that depend on LDP. If LDP must remain enabled, restrict LDP peering to trusted adjacent routers using firewall filters or ACLs that permit LDP (port 646) only from authorized neighbors, and enable LDP MD5 authentication where supported; note that authentication does not stop a compromised or malicious established LDP peer from sending crafted messages and may not fully mitigate the issue. Additionally, monitor rpd for crashes and consider routing protocol graceful restart or nonstop routing to reduce downtime, though these do not prevent the flaw. Refer to the vendor advisory for the latest mitigation guidance.

Affected VersionsENISA

Junos OS 24.4 <24.4R2-S5
Junos OS 24.2 <24.2R2-S5.5
Junos OS 25.2 <25.2R2-S2
Junos OS Evolved 25.2 <25.2R2-S2-EVO
Junos OS 23.4 <23.4R2-S8.13
Junos OS Evolved 25.2X100 <25.2X100-D35-EVO
Junos OS Evolved 23.4X100
Junos OS Evolved 25.4X300 <25.4X300-D40-EVO
Junos OS Evolved 25.4 <25.4R1-S3-EVO
Junos OS 26.2 <26.2R1-S2
Junos OS Evolved 24.4 <24.4R2-S5-EVO
Junos OS 25.4 <25.4R1-S3
Junos OS Evolved 24.2 <24.2R2-S5.6-EVO
Junos OS Evolved 23.4 <23.4R2-S8.11-EVO
Junos OS Evolved 26.2 <26.2R1-S2-EVO

Affected Packages

euvd junos_os fix: 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 26.2R1-S2
euvd junos_os_evolved fix: 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, 25.4X300-D40-EVO, 26.2R1-S2-EVO

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability is a NULL pointer dereference (CWE-476) in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved. rpd handles routing protocols including Label Distribution Protocol (LDP), which is used to distribute MPLS labels between adjacent routers. An attacker who already has an operational LDP session with the target can send a specially crafted LDP message that causes rpd to dereference a NULL pointer, leading to a crash and denial of service. The CPE data lists all versions of junos_os and junos_os_evolved with wildcard version fields, indicating the flaw affects the operating systems generally rather than a specific release range in the provided data. The CVSS 4.0 vector (AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L) and the independent CVSS 3.1 assessment (AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) confirm an adjacent, unauthenticated, availability-only impact; no confidentiality or integrity impact is assessed. Exploitation is limited by the need for MPLS/LDP to be enabled and a live LDP session to exist.

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Severity by source

Vendor (juniper) PRIMARY 7.1 MEDIUM
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L
vuln.today AI 6.5 MEDIUM

Adjacent unauthenticated LDP peer (AV:A, PR:N) sends low-complexity crafted message (AC:L); impact is rpd crash with availability loss only (A:H, C:N/I:N), no scope change.

3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

Primary rating from Vendor (juniper).

CVSS VectorVendor: juniper

Attack Vector
Adjacent
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
Low

Lifecycle Timeline

4
Patch available
Oct 14, 2026 - 18:05 EUVD
Severity Changed
Oct 14, 2026 - 17:22 NVD
MEDIUM HIGH
CVSS changed
Oct 14, 2026 - 17:22 NVD
6.5 (MEDIUM) 7.1 (HIGH)
CVE Published
Oct 14, 2026 - 16:32 cve.org
MEDIUM 6.5

DescriptionCVE.org

A NULL Pointer Dereference vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a denial of service via LDP messages received over an operational LDP session.

Executive ViewAI

Why It Matters

A high-severity availability flaw in Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated attacker on an adjacent network segment who is already an established LDP peer to crash the routing protocol daemon (rpd), disrupting routing and MPLS-dependent connectivity on affected devices. Only environments running MPLS with LDP configured and an active LDP session are exposed, so impact is concentrated in service-provider, WAN, and large enterprise core networks where outages translate directly into customer-facing or revenue-impacting downtime. No vendor patch is currently available, and no public exploit has been identified at time of analysis, giving leadership a limited but real window to reduce exposure through network-level controls.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: disable MPLS/LDP where not operationally required; restrict LDP (TCP/UDP 646) to an explicit allowlist of trusted adjacent peers via interface ACLs and control-plane policing; block LDP traffic from untrusted adjacent segments; enable LDP authentication where supported; monitor and alert on routing protocol daemon (rpd) crashes or restarts; and maintain a rollback/backup routing path for MPLS-dependent services.

Threat Intelligence Overview

EPSS Score
0.3%
Top 82% exploitable
Prevalence
High
Juniper Junos OS is widely deployed enterprise/carrier routing platform
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Controlled
Automatable
No
Human Impact
High
Technical Impact
Partial

Priority Score

36
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +36
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A null pointer dereference occurs when a program attempts to access memory through a pointer that has been set to NULL (address 0x0).

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