Threats / Juniper / CVE-2023-36851
CVE-2023-36851
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
Juniper Junos OS vulnerability
Juniper Junos OS on SRX Series contains missing authentication for a critical function, allowing unauthenticated network attackers to upload arbitrary files via J-Web and compromise file system integrity.
Verdict
Today item — known-exploited.
An unauthenticated, network-based attacker can exploit missing authentication on webauth_operation.php to upload arbitrary files to the SRX device, degrading file system integrity and potentially enabling further exploitation.
CISA KEV Yes · 2023-11-135EPSS 0.01123 (verify live)6CVSS 5.33CISA SSVC Exploitation: active · Automatable: yes · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
5 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-11-13).
Probability (EPSS)
EPSS 0.01123 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
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.
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.
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.
Currency of the record
CISA added this to its KEV catalog 48 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.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution 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 board1
Front door — unauthenticated access narrative 1
Attacker
I identify the unauthenticated webauth_operation.php endpoint exposed on the J-Web interface.
Business
The organization's SRX device exposes a critical administrative function without requiring authentication.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I craft a request to upload an arbitrary file through the vulnerable endpoint without providing credentials.
Business
An attacker gains the ability to write files to the device without any access controls.
3
Lateral reach — past segmentation narrative 3
Attacker
I place malicious or unauthorized files on the SRX device's file system.
Business
The device's file system integrity is compromised, creating a foothold for privilege escalation or lateral movement.
4
Data at risk — exfiltration narrative 4
Attacker
I chain this vulnerability with other flaws to achieve code execution or administrative access.
Business
The organization faces potential loss of network security posture and control over critical 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’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by juniperCNA
Credited with finding itThe Juniper SIRT would like to acknowledge and thank watchtowr for responsibly reporting this vulnerability.finder
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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