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Threats / Juniper / CVE-2023-36846
CVE-2023-36846 · EUVD no mirror located · GCVE no mirror located Verified 2026-08-04

Juniper Junos OS vulnerability

Juniper Junos OS on SRX Series contains a missing authentication vulnerability in J-Web that allows unauthenticated attackers to upload arbitrary files, compromising file system integrity.

Verdict

Today item — known-exploited.

An unauthenticated network attacker can exploit a missing authentication check in the user.php endpoint to upload malicious files via J-Web, potentially enabling further compromise of the device.

CISA KEV Yes · 2023-11-135EPSS 0.94205 (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
18 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 0.94205 — 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 that the user.php endpoint in J-Web lacks authentication controls.
Business
The organization's SRX device perimeter security is exposed to unauthorized file upload attacks without credential requirements.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
I craft a request to upload arbitrary files to the device file system without providing valid credentials.
Business
Malicious files are written to the device, degrading the integrity of critical system components.
3

Lateral reach — past segmentation narrative 3

Attacker
I chain this file upload capability with other vulnerabilities to achieve deeper system compromise.
Business
The organization faces potential loss of device control, configuration tampering, or lateral movement into the network.
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)
  • 18 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