Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.58% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-101986High confidence
Junos OS and Junos OS Evolved: J-Web permits pre-authentication CGI execution
Juniper Networks · Junos OS
9.3CriticalCVSS 4.0
Within 72 hours
Patch availableCritical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityCritical→Operational priority:Critical, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Juniper Networks Junos OS and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.
Patch available01
What, why and how
An Improper Authentication vulnerability in J-Web of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network attacker to bypass J-Web authentication and execute CGI content with elevated privileges via a crafted HTTP request.
What
An Improper Authentication vulnerability in J-Web of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network attacker to bypass J-Web authentication and execute CGI content with elevated privileges via a crafted HTTP request.
Why
The affected component does not establish the requesting party's identity reliably before granting access.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may gain additional privileges.
What
An Improper Authentication vulnerability in J-Web of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network attacker to bypass J-Web authentication and execute CGI content with elevated privileges via a crafted HTTP request.
Why
The affected component does not establish the requesting party's identity reliably before granting access.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may gain additional privileges.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Improper Authentication → gain additional privileges
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-287 ↗
CWE-287: Improper Authentication. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:LCommon Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SALowSubsequent-system availability: A successful attack can cause a limited loss.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- Junos OS Evolved: 25.2 < 25.2R2-S2-EVO, 23.4X100, 25.2X100 < 25.2X100-D35-EVO, 25.4 < 25.4R1-S3-EVO, 25.4X300 < 25.4X300-D40-EVO, 0 < 23.2R2-S7.7-EVO, 26.2 < 26.2R1-S2-EVO, 24.2 < 24.2R2-S5.6-EVO, 24.4 < 24.4R2-S5-EVO, 23.4 < 23.4R2-S8.11-EVO
- Junos OS: 24.2 < 24.2R2-S5.5, 24.4 < 24.4R2-S5, 25.4 < 25.4R1-S3, 0 < 23.2R2-S7.7, 25.2 < 25.2R2-S2, 23.4 < 23.4R2-S8.13, 26.2 < 26.2R1-S2
- Fixed
- The following software releases have been updated to resolve this specific issue:
- Junos OS: 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 25.4R2, 26.2R1-S2, 26.2R2, 26.4R1, and all subsequent releases.
- Junos OS Evolved: 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, 25.4R2-EVO, 25.4X300-D40-EVO, 26.2R1-S2-EVO, 26.2R2-EVO, 26.4R1-EVO, and all subsequent releases.
- Note: For Junos OS releases 23.2, 23.4, and 24.2, and Junos OS Evolved releases 23.2-EVO, 23.4-EVO, and 24.2-EVO, specific respins have been referenced. Previously published versions of these releases have been rebuilt to resolve the security vulnerabilities identified in this advisory.
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 14 Oct 2026 · Last source change 15 Oct 2026, 03:57 UTC · CWE-287 · Improper Authentication
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-10-15
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-101450
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD awaiting enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- ENISA EUVD mappingEUVD-2026-101450 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-101450"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Fixed release or patch reference recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.