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Session Smart Router EUVDEUVD-2026-112221

| CVE-2026-103400 MEDIUM
Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (CWE-74)
2026-10-28 juniper GHSA-hf87-h3v7-pm52
5.5
CVSS 3.1 · NVD
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Attack ChainAIDerived

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

  1. Access
    Obtain low-privileged local shell on device
  2. Delivery
    Create specially named directories targeting ember
  3. Exploit
    Trigger ember service restart
  4. Execution
    Service unmounts filesystems / crashes
  5. Impact
    Denial of service on router or conductor

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Input neutralization, injection prevention
Exploitation Conditions

Exploitation requires local access to the Session Smart Router or Conductor with low-level privileges (PR:L) sufficient to create directories read by the ember service, plus the ability to cause a service restart for the crafted directory names to take effect. The specific prerequisite is the creation of specially named directories that the ember service improperly neutralizes, triggering arbitrary filesystem unmounts or a crash. Limiting factors: there is no network vector (AV:L), the attacker must already be authenticated on the device, and impact is confined to availability (C:N/I:N/A:H) with no confidentiality or integrity exposure; a service restart must occur for the condition to manifest.

Impact

This is a moderate-severity, availability-only issue that does not rise to an urgent priority despite the vendor's 'this_month' decision label. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, base 5.5) confines the attack to a local, already-authenticated actor and limits impact to availability (A:H) with no confidentiality or integrity effect. No EPSS score was supplied, the CVE is not listed in CISA KEV, and no public exploit or PoC reference is provided, so there is no public exploit identified at time of analysis. The signals are internally consistent - a locally-exploitable DoS reported by the vendor itself - and none conflict, but note that key triage data (EPSS probability, SSVC automatable/technical-impact values) is absent, so the ranking rests on CVSS plus the vendor's 'this_month' label rather than observed exploitation. Overall this reads as a genuine but bounded operational-availability risk requiring an existing foothold, not a high-urgency remotely-exploitable flaw.

Exploit ScenarioDerived

An attacker who already has low-privileged local access to a Session Smart Router or Conductor creates one or more specially named directories that the ember service mishandles, then triggers a service restart. On restart the crafted names cause the ember service to unmount arbitrary filesystems or fail, producing a denial of service. No public exploit is identified at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available

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AnalysisAIv1 – Oct 28, 2026

Local users with low privileges on Juniper Networks Session Smart Router and Session Smart Conductor can force arbitrary filesystem unmounts or a denial-of-service condition in the ember service by creating directories with specially crafted names and then triggering a service restart. The flaw is an output-neutralization (injection) weakness rated CVSS 5.5 with impact confined to availability (C:N/I:N/A:H); the vector requires local access and low privileges (AV:L/PR:L) and no user interaction. No public exploit code and no confirmed active exploitation were identified at time of analysis, and the vendor-priority label places remediation within this month rather than as an emergency.

RemediationAI

No vendor-released patch version is identified in the available data; consult Juniper advisory JSA112183 (https://supportportal.juniper.net/JSA112183) for the affected release matrix and the exact fixed software versions to upgrade to, and apply the upgrade to both Session Smart Router and Session Smart Conductor as applicable. Because the vector is local with low privileges (AV:L/PR:L), the compensating controls indicated by the assessed prerequisites are to restrict local shell/CLI accounts on routers and conductors to trusted administrators and to remove or tightly scope spare low-privileged accounts, with the trade-off that operational and support workflows needing on-box access must be re-provisioned through privileged or brokered access. Avoid unnecessary restarts of the ember service on hosts where untrusted users can write directories, since a restart is the step that makes crafted directory names take effect; the trade-off is that legitimate maintenance restarts must be scheduled deliberately. No additional mitigations are stated in the available sources.

Affected VersionsENISA

Session Smart Conductor 7.1.0 <7.1.7
Session Smart Router 0 <7.0.5
Session Smart Conductor 0 <7.0.5
Session Smart Router 7.2.0 <7.2.3
Session Smart Router 7.1.0 <7.1.7
Session Smart Conductor 7.2.0 <7.2.3

Affected Packages

euvd session_smart_conductor fix: 7.0.5, 7.1.7, 7.2.3
euvd session_smart_router fix: 7.0.5, 7.1.7, 7.2.3

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 weakness is classified as CWE-74, Improper Neutralization of Special Elements in Output Used by a Downstream Component, which is the injection parent class rather than a specific sink. In this instance the vulnerable component is the ember service on Session Smart Router and Session Smart Conductor, which consumes directory names present on the local filesystem and fails to neutralize special elements in them before that data reaches a downstream consumer; the crafted names subsequently cause filesystem unmount operations or a crash. The CVSS 3.1 vector AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H describes severity, not mechanism: it confirms that the attacker must operate locally with some authenticated low-level access, that no user interaction is needed, that the scope is unchanged, and that only availability is impacted, with no confidentiality or integrity exposure. The input data does not state which internal parsing or command-construction path in ember is reached, so the precise trigger beyond crafted directory names plus a service restart is not described in the available sources; the restart is required for the crafted names to take effect. Affected platforms are those carrying the Session Smart Router and Session Smart Conductor CPE entries, with no version boundaries enumerated in the supplied data.

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Severity by source

Vendor (juniper) PRIMARY MEDIUM
NVD 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI 5.5 MEDIUM

Requires authenticated local access to create directories read by the ember service, so AV:L and PR:L; impact is availability-only (unmount/DoS), hence C:N/I:N/A:H.

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

Primary rating from Vendor (juniper).

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

1
Patch available
Oct 28, 2026 - 17:19 EUVD

DescriptionNVD

An Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') vulnerability in the ember service in Juniper Networks Session Smart Router and Session Smart Conductor allows an attacker with local access to unmount arbitrary filesystems or cause a denial of service via the creation of specially named directories and a service restart.

Threat Intelligence Overview

Prevalence
Medium
specific vendor SD-WAN appliance, deployed but not ubiquitous
Data Quality
3 sources
Confidence: Low

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 MEDIUM
CISA KEV No
Public POC No
EPSS N/A
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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· derived
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

28
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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