Medium

CVE-2026-33803 — Junos OS Evolved: A port which has been inadvertently exposed can be reached by an attacker

An Improper Restriction of Communication Channel to Intended Endpoints vulnerability in Juniper Networks Junos OS Evolved allows an unauthenticated, network-based attacker to cause a limited information disclosure and availability impact to the device. Due to a wrong initialization, a process which should only be able to communicate internally within the device can be reached over the network via an open port. This leads to a device being inadvertently exposed and increased CPU cycles spent processing ingress packets. This issue affects Junos OS Evolved: * all versions before 23.2R2-S7-EVO, * 23.4 versions before 23.4R2-S8-EVO, * 24.2 versions before 24.2R2-S5-EVO, * 24.4 versions before 24.4R2-S4-EVO, * 25.2 versions before 25.2R2-S1-EVO, * 25.4 versions before 25.4R1-S2-EVO.

Published Jul 9, 2026 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: juniper

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.4% (30-day exploitation probability)+4
Technical severity (medium)+3
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.35%

ahead of 27% of scored CVEs · Oct 15, 2026

Affects

Juniper Networks

Junos Os Evolved

CVSS base

6.5

Medium · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Juniper Networks Junos Os Evolved).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Juniper Networks	Junos Os Evolved	version 25.2-r1version 24.2-r2-s1version 24.2-r2-s2version 24.2-r2-s3version 24.2-r2-s4version 24.4version 24.4-r1version 24.4-r1-s2 and 40 more version 24.4-r1-s3version 24.4-r2version 24.4-r2-s1version 24.4-r2-s2version 24.4-r2-s3version 25.2version 24.2-r2version 25.2-r1-s1version 25.2-r1-s2version 25.2-r2version 25.4version 25.4-r1version 25.4-r1-s1version 23.4-r1-s1version 23.2version 23.2-r1version 23.2-r1-s1version 23.2-r1-s2version 23.2-r2version 23.2-r2-s1version 23.2-r2-s2version 23.2-r2-s3version 23.2-r2-s4version 23.2-r2-s5version 23.2-r2-s6version 23.4version 23.4-r1< 23.2version 23.4-r1-s2version 23.4-r2version 23.4-r2-s1version 23.4-r2-s2version 23.4-r2-s3version 23.4-r2-s4version 23.4-r2-s5version 23.4-r2-s6version 23.4-r2-s7version 24.2version 24.2-r1version 24.2-r1-s2	Vulnerable	NIST National Vulnerability Database
Juniper Networks	Junos Os Evolved	< 23.2R2-S7-EVO≥ 23.4 and < 23.4R2-S8-EVO≥ 24.2 and < 24.2R2-S5-EVO≥ 24.4 and < 24.4R2-S4-EVO≥ 25.2 and < 25.2R2-S1-EVO≥ 25.4 and < 25.4R1-S2-EVO	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

Low

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
6.9	CVSS 4.0	Medium	—	—	sirt@juniper.net via NIST National Vulnerability Database
6.9	CVSS 4.0	Medium	—	—	juniper via CVE Program (cve.org) e CISA ADP
6.5	CVSS 3.1	Medium	3.9	2.5	sirt@juniper.net via NIST National Vulnerability Database
6.5	CVSS 3.1	Medium	—	—	GitHub, Inc. via GitHub Security Advisories
6.5	CVSS 3.1	Medium	—	—	juniper via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L (score shown at the top: sirt@juniper.net)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-923

Other CVEs with this weakness →

EPSS over time FIRST

Oct 14, 2026 → Oct 15, 2026 · 2 reading(s) · max 0.35%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · juniper networks/junos os evolved
Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 14, 2026
Affected products added · juniper/junos os evolved
Oct 14, 2026 · NIST National Vulnerability Database
CVSS changed · 6.5
Oct 14, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 14, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 14, 2026 · Alertas do Telegram
CVE published
Jul 9, 2026 · juniper

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 14, 2026 – Oct 14, 2026
1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

3 on the record

supportportal.juniper.net/JSA110078
Vendor Advisory, vendor-advisory, NIST National Vulnerability Database
github.com/advisories/GHSA-xc4g-8c26-vcmf
GitHub Security Advisories
nvd.nist.gov/vuln/detail/CVE-2026-33803
GitHub Security Advisories

Elsewhere on this site

Juniper Networks
every CVE for this vendor

CWE-923
other pages naming this weakness

Related CVEs (same products)

Critical CVE-2026-101982 Junos OS and Junos OS Evolved: A EVPN peer causes an rpd crash or root-level compromise when EVPN-VPWS is used 1d
Critical CVE-2026-101983 Junos OS and Junos OS Evolved: An attacker causes remote code execution when J-Web virtual-domain is configured 1d
High CVE-2026-101979 Junos OS and Junos OS Evolved: A network attacker causes root-level code execution or denial of service when SNMP and AAA are enabled 1d
High CVE-2026-101976 Junos OS and Junos OS Evolved: In a non-4byte-AS scenario a specific BGP update causes an rpd crash 1d
Medium CVE-2026-101972 Junos OS and Junos OS Evolved: Malformed OSPF packets causes routing disruption when OSPF is enabled 1d
Medium CVE-2026-101964 Junos OS and Junos OS Evolved: An attacker can cause an rpd crash via a crafted LDP message 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-33803 is "Junos OS Evolved: A port which has been inadvertently exposed can be reached by an attacker", rated Medium. It affects Junos Os Evolved (Juniper Networks); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.5 describes technical severity. EPSS 0.35% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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