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Junos OS Evolved EUVDEUVD-2026-101348

| CVE-2026-102023 HIGH
Reachable Assertion (CWE-617)
2026-10-14 juniper GHSA-whvc-jqf2-crr7
8.7
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
    Obtain SNMP access to device
  2. Exploit
    Send crafted firewall-counter MIB query
  3. Execution
    Trigger reachable assertion in fwstatsd
  4. Impact
    Daemon crash causes denial of service

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V16 - Security Logging and Error Handling Reachable assertion handling
Exploitation Conditions

Exploitation requires that at least one firewall counter be explicitly configured on the Junos OS Evolved device - if no firewall counter exists, the vulnerable fwstatsd code path is not reachable. The attacker must also have SNMP reachability to the device and, per the advisory description, authenticated SNMP access (valid community string / SNMPv3 credentials) to issue the firewall-counter MIB query. Limiting factors: the dependency on an existing firewall-counter configuration (not guaranteed on every deployment), the need for SNMP to be enabled and reachable on an exposed interface, and the stated authentication requirement - the CVSS vector's PR:N appears to contradict this and should be verified against Juniper's advisory.

Impact

This is a genuine but bounded operational risk rather than a top-tier emergency. The CVSS 4.0 base score of 8.7 (High) is driven entirely by availability impact (VA:H) with no confidentiality or integrity exposure (VC:N/VI:N) - consistent with CWE-617 (Reachable Assertion), which crashes a process rather than yielding code execution or data. The input provides no EPSS score, no CISA KEV listing, and no indication of public exploit code, so based on available signals this is 'no public exploit identified at time of analysis.' A key conflict must be flagged: the supplied CVSS 4.0 vector contains PR:N (no privileges), yet the description explicitly states an 'authenticated network attacker' and the attack is an SNMP MIB query, which in practice requires valid SNMP credentials/community access - verify the true privilege requirement with Juniper, as PR:N likely understates the access needed. The CVSS supplemental metrics reinforce moderate operational concern: AU:Y (Automatable) and R:A (Recovery: Automatic) suggest the attack can be scripted but the device self-recovers, limiting lasting damage. Net: prioritize for patching on exposed management planes, but the authentication requirement, availability-only impact, and absence of any exploitation evidence place it below internet-facing unauthenticated RCE class issues.

Exploit ScenarioDerived

An attacker with SNMP access to the management interface of a Junos OS Evolved device that has at least one firewall counter configured sends a crafted firewall-counter MIB query. The query triggers a reachable assertion in the fwstatsd daemon, crashing it and causing a denial of service against firewall statistics processing. No public proof-of-concept is identified at time of analysis, and the low attack complexity (AC:L) means the request itself is simple once SNMP reachability and credentials are obtained.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 14, 2026

Denial of service in Juniper Networks Junos OS Evolved can be triggered by a crafted SNMP query to the firewall-counter MIB, causing the fwstatsd daemon to hit a reachable assertion and terminate, which disrupts device availability when at least one firewall counter is configured. The advisory describes an authenticated network attacker and the independent assessment's CVSS 3.1 vector (PR:L) reflects an authenticated prerequisite, while the supplied CVSS 4.0 vector lists PR:N, an inconsistency that should be verified against Juniper's advisory. No public exploit code or active exploitation has been identified at time of analysis.

RemediationAI

No exact fixed version is provided in the available data; consult Juniper advisory JSA112250 for the vendor-released patched Junos OS Evolved release and upgrade to that version (patch available per vendor advisory). If an immediate upgrade is not possible, restrict SNMP access with firewall filters or ACLs so only trusted management subnets can reach the device, and disable SNMP entirely if it is not operationally required. Where SNMP must remain enabled, configure SNMP views to deny access to the firewall-counter MIB objects, and avoid configuring firewall counters if they are not needed, understanding that this reduces firewall statistics visibility. Each workaround carries trade-offs: disabling SNMP or restricting its reachability degrades monitoring and management automation, view-based blocking may be bypassed by broad community strings if not combined with network controls, and omitting firewall counters may impair troubleshooting.

Affected VersionsENISA

Junos OS Evolved 26.2 <26.2R1-S2-EVO
Junos OS Evolved 25.4 <25.4R1-S3-EVO
Junos OS Evolved 25.4X300 <25.4X300-D40-EVO
Junos OS Evolved 24.2 <24.2R2-S5.6-EVO
Junos OS Evolved 0 <23.2R2-S7.7-EVO
Junos OS Evolved 24.4 <24.4R2-S5-EVO
Junos OS Evolved 25.2 <25.2R2-S2-EVO
Junos OS Evolved 23.4X100
Junos OS Evolved 25.2X100 <25.2X100-D35-EVO
Junos OS Evolved 23.4 <23.4R2-S8.11-EVO

Affected Packages

euvd junos_os_evolved fix: 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, 25.4X300-D40-EVO, 26.2R1-S2-EVO

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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

Technical ContextAI · show details

fwstatsd is a Junos OS Evolved daemon responsible for handling firewall statistics; the vulnerability is classified as CWE-617 (Reachable Assertion), meaning a network-reachable code path leads to an assert() failure rather than a memory-safety corruption. The trigger is an SNMP query against the firewall-counter MIB (e.g., jnxFirewall* counter tables), which fwstatsd processes when at least one firewall counter exists in the configuration. Junos OS Evolved is the Linux-based, modular operating system for certain Juniper platforms, identified by CPE cpe:2.3:a:juniper_networks:junos_os_evolved. The CVSS 4.0 vector scores 8.7 with AV:N/AC:L/AT:N/PR:N/UI:N, showing only high availability impact on the vulnerable system (VA:H) and low subsequent availability impact (SA:L), with no confidentiality or integrity impact. The relatively low attack complexity and network vector make the issue concerning where SNMP is enabled and reachable.

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Severity by source

Vendor (juniper) PRIMARY 8.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M
vuln.today AI 6.5 MEDIUM

SNMP query is network-reachable and simple (AV:N/AC:L); description states an authenticated attacker so PR:L; only the fwstatsd service availability is affected (A:H, C:N/I:N).

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/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 VectorVendor: juniper

Attack Vector
Network
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

3
Patch available
Oct 14, 2026 - 18:05 EUVD
CVSS changed
Oct 14, 2026 - 17:22 NVD
7.5 (HIGH) 8.7 (HIGH)
CVE Published
Oct 14, 2026 - 16:47 cve.org
HIGH 8.7

DescriptionCVE.org

A Reachable Assertion vulnerability in fwstatsd of Juniper Networks Junos OS Evolved allows an authenticated network attacker to cause a denial of service via an SNMP firewall-counter MIB query when at least one firewall counter is configured.

Executive ViewAI

Why It Matters

Juniper Networks Junos OS Evolved is affected by a high-severity denial-of-service vulnerability that can cause network devices to become unavailable, disrupting critical business connectivity and services. No vendor-released patch identified at time of analysis, and while no public exploit identified at time of analysis, the lack of a fix leaves organizations exposed. Leadership should prioritize implementing interim mitigations to protect affected infrastructure.

Business Impact: High
Compensating Controls

Restrict SNMP access to trusted management networks, disable SNMP if not required, apply ACLs to block SNMP from untrusted sources, monitor for fwstatsd daemon crashes, and consider disabling firewall counters if feasible.

Threat Intelligence Overview

EPSS Score
0.5%
Top 62% exploitable
Prevalence
Medium
specific Juniper carrier/enterprise network OS variant, not universally deployed
Data Quality
4 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 0.5%
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
Open
Automatable
Yes
Human Impact
High
Technical Impact
Partial

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
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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