CyberSecBulletin
CVE-2026-101954NVD status: Awaiting Analysis

Junos OS: Improper Authentication

Published Updated By the CyberSecBulletin desk

CVE-2026-101954 is a critical-severity improper authentication vulnerability in Junos OS from Juniper Networks, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 25.2R2-S2, 25.4R1-S3, 26.2R1-S2 as the first without the flaw, so updating Junos OS to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.48% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Junos OS to 25.2R2-S2 or 25.4R1-S3 or 26.2R1-S2, whichever matches your release line, or a later version.
  2. Update Junos OS Evolved to 25.2R2-S2-EVO or 25.4R1-S3-EVO or 26.2R1-S2-EVO or 25.2X100-D35-EVO, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Juniper NetworksJunos OS25.2 up to, but not including, 25.2R2-S2; 25.4 up to, but not including, 25.4R1-S3; 26.2 up to, but not including, 26.2R1-S225.2R2-S2, 25.4R1-S3, 26.2R1-S2
Juniper NetworksJunos OS Evolved25.2 up to, but not including, 25.2R2-S2-EVO; 25.4 up to, but not including, 25.4R1-S3-EVO; 26.2 up to, but not including, 26.2R1-S2-EVO; 23.4X100; 25.2X100 up to, but not including, 25.2X100-D35-EVO; 25.4X300 up to, but not including, 25.4X300-D40-EVO25.2R2-S2-EVO, 25.4R1-S3-EVO, 26.2R1-S2-EVO, 25.2X100-D35-EVO, 25.4X300-D40-EVO

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (juniper.net).

Scoring systemScoreSeverityScored by
CVSS 4.09.3CriticalCNA (juniper.net)
CVSS 3.19.8CriticalCNA (juniper.net)

Official description

An Improper Authentication vulnerability in the J-Web management interface and its NETCONF session handling of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network attacker to obtain root-level device configuration access and take over the device via a reachable J-Web HTTP or HTTPS service when web management is enabled.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

How developers prevent this class of flaw

  • Use an authentication framework or library such as the OWASP ESAPI Authentication feature.

More Improper Authentication vulnerabilities (CWE-287)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Junos OS

All Junos OS vulnerabilities

Recent Improper Authentication vulnerabilities

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