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Threats / Juniper / CVE-2023-36844
CVE-2023-36844 · EUVD no mirror located · GCVE no mirror located Verified 2026-08-04

Juniper Junos OS vulnerability

Juniper Junos OS on EX Series contains a PHP external variable modification vulnerability allowing unauthenticated network attackers to control environment variables, potentially enabling further exploitation.

Verdict

Today item — known-exploited.

An unauthenticated remote attacker can modify PHP environment variables on affected Junos OS EX Series devices through crafted requests. This integrity compromise may facilitate chaining to additional vulnerabilities for greater impact.

CISA KEV Yes · 2023-11-135EPSS 0.91357 (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
493 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 ↗dashboard.shadowserver.o ↗Confirmed
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-11-13).
CISA KEV ↗Confirmed
Probability (EPSS)
EPSS 0.91357 — 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-473 CWE-473.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
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
nuclei ↗Confirmed
WeaknessCWE-473 · CWE-473
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 craft a network request targeting PHP environment variable handling on the EX Series device without requiring authentication.
Business
The device's configuration integrity is compromised, creating an entry point for secondary attacks that could disrupt network operations.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
I modify critical PHP environment variables to alter application behavior or bypass security controls on the affected system.
Business
Attackers gain a foothold to chain this vulnerability with others, potentially leading to unauthorized access or system compromise.
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)
  • 493 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