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Threats / Juniper / CVE-2023-36847
CVE-2023-36847 · EUVD no mirror located · GCVE no mirror located Verified 2026-08-04

Juniper Junos OS vulnerability

Juniper Junos OS on EX Series lacks authentication for the installAppPackage.php function, allowing unauthenticated attackers to upload arbitrary files via J-Web and compromise file system integrity.

Verdict

Today item — known-exploited.

An unauthenticated network attacker can upload arbitrary files to affected EX Series devices through an unprotected J-Web endpoint, degrading file system integrity and potentially enabling further exploitation chains.

CISA KEV Yes · 2023-11-135EPSS 0.84692 (verify live)6Exploit Weaponized · public PoC7CVSS 5.33CISA SSVC Exploitation: active · Automatable: yes · Impact: total4
01

Is it exploitable?

— the evidence, ranked above the score
Exploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
vulncheck.com ↗vulncheck.com ↗Confirmed
Reported exploitation
8 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
twitter.com ↗supportportal.juniper.ne ↗cisa.gov ↗cisa.gov ↗Confirmed
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-11-13).
CISA KEV ↗Confirmed
Probability (EPSS)
EPSS 0.84692 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
FIRST EPSS ↗High
Severity / affected
CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N) · Affected: Juniper, Junos OS. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
CVE.org ↗Reported
Weakness (CWE)
Mapped to CWE-306 Missing Authentication — weakness family: Authentication.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CVE.org ↗Reported
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
CISA-ADP ↗Reported
Currency of the record
CISA added this to its KEV catalog 88 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
CISA KEV ↗CVE.org ↗Reported
WeaknessCWE-306 · Missing AuthenticationAuthentication
02

Who’s exploiting it?

— attribution turns risk into urgency
Attribution not established

No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.

03

Why it matters

— the attack path, told twice: adversary, then board
1

Front door — unauthenticated access narrative 1

Attacker
I identify the unprotected installAppPackage.php endpoint accessible without credentials on the J-Web interface.
Business
The organization's network device exposes a critical administrative function to any network-connected party.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
I craft and send a request to upload a malicious file to the device file system without providing authentication.
Business
Arbitrary file placement compromises the integrity and trustworthiness of the device's operating environment.
3

Lateral reach — past segmentation narrative 3

Attacker
I leverage the uploaded file as a pivot point to chain additional exploits or establish persistence on the device.
Business
The initial file upload vulnerability becomes a staging ground for deeper compromise of network infrastructure.
04

What to do

— defensible action
  • Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05

Coverage & confidence

— what we know, and what we don’t

Established (cited)

  • KEV listing (CISA)
  • EPSS probability (FIRST)
  • Weaponized exploit available (VulnCheck)
  • 8 reported-exploitation source(s)
  • CVSS 5.3 — CNA-assigned (CVE.org)
  • CISA SSVC triage disposition (CVE.org ADP)
  • CWE weakness mapping — CNA-assigned (CVE.org)
  • Public exploit availability
  • Catalogued by juniper (CNA)
  • Named finder/reporter credit (CVE.org)

    • Coverage gaps — stated, not hidden

  • No EUVD / GCVE mirror in feed — single-authority dependency for the identifier.
  • EPSS & exposure are time-varying; verify live at the source.
  • Threat-actor attribution not established from feed data — absence of a name is not absence of compromise.
    • Disclosure & credit2
    Catalogued by juniperCNA
    Credited with finding itLYS, working with DEVCORE Internship Programfinder