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ExploitedIn CISA KEVFix available

CVE-2023-36844

Exploitation confirmed. First attested on 2023-10-14 by CISA-ADP, CISA KEV, GCVE · kevintel, GCVE · shadowserver.

  • Published2023-08-17
  • Fixed in20.4
  • WeaknessCWE-473

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series allows an unauthenticated, network-based attacker to control certain, important environment variables. Using a crafted request an attacker is able to modify certain PHP environment variables leading to partial loss of integrity, which may allow chaining to other vulnerabilities. This issue affects Juniper Networks Junos OS on EX Series: * All versions prior to 20.4R3-S9; * 21.1 versions 21.1R1 and later; * 21.2 versions prior to 21.2R3-S7; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3-S5; * 22.1 versions prior to 22.1R3-S4; * 22.2 versions prior to 22.2R3-S2; * 22.3 versions prior to 22.3R3-S1; * 22.4 versions prior to 22.4R2-S2, 22.4R3; * 23.2 versions prior to 23.2R1-S1, 23.2R2.

Timeline

dates in UTC
  1. 2023-08-1720:15CVE publishedNVD
  2. 2023-10-1416:00Listed as exploited by GCVEGCVE
  3. 2023-10-1416:00Exploitation first reportedGCVE
  4. 2023-11-13Added to the CISA KEV catalogCISA KEV
  5. 2023-11-1516:40SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2023-36844?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2023-36844?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Juniper junosversion to verify
BranchAffectedFixed in
20.4< 20.420.4
21.2= 21.2no fix published
20.4= 20.4no fix published
21.1= 21.1no fix published
21.3= 21.3no fix published
21.4= 21.4no fix published
22.1= 22.1no fix published
22.2= 22.2no fix published
22.3= 22.3no fix published
22.4= 22.4no fix published
23.2= 23.2no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As juniper, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Juniper Networks Junos OSother versions: not affected

    platforms: EX Series

    Affected
    • < 20.4R3-S9fixed in 20.4R3-S9semver
    • ≥ 21.1, < 21.1*fixed in 21.1*semver
    • ≥ 21.2, < 21.2R3-S6fixed in 21.2R3-S6semver
    • ≥ 21.3, < 21.3R3-S5fixed in 21.3R3-S5semver
    • ≥ 21.4, < 21.4R3-S5fixed in 21.4R3-S5semver
    • ≥ 22.1, < 22.1R3-S4fixed in 22.1R3-S4semver
    • ≥ 22.2, < 22.2R3-S2fixed in 22.2R3-S2semver
    • ≥ 22.3, < 22.3R3-S1fixed in 22.3R3-S1semver

    2 more version lines in the CVE record.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2023-10-02

Fix

  1. Update Juniper junos to 20.4
  2. CISA’s required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.due 2023-11-17

Advisories and patches

Detection

read 2026-11-02 22:42 UTC
Nuclei template
available
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
3 repositories, unverifiedwatchtowrlabs/juniper-rce_cve-2023-36844Ap0dexMe0/CVE-2023-36844r3dcl1ff/CVE-2023-36844_Juniper_RCE
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2023-11-13
Patch Due Date
2023-11-17
Ransomware Use
Unknown
Required Action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Published
2023-08-17
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-f2v8-3pfh-v3xm

Frequently asked questions

What is CVE-2023-36844?

A PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series allows an unauthenticated, network-based attacker to control certain, important environment variables. Using a crafted request an attacker is able to modify certain PHP environment variables leading to partial loss of integrity, which may allow chaining to other vulnerabilities. This issue affects Juniper Networks Junos OS on EX Series: * All versions prior to 20.4R3-S9; * 21.1 versions 21.1R1 and later; * 21.2 versions prior to 21.2R3-S7; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3-S5; * 22.1 versions prior to 22.1R3-S4; * 22.2 versions prior to 22.2R3-S2; * 22.3 versions prior to 22.3R3-S1; * 22.4 versions prior to 22.4R2-S2, 22.4R3; * 23.2 versions prior to 23.2R1-S1, 23.2R2.

Is CVE-2023-36844 actively exploited?

Yes. CVE-2023-36844 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2023-11-17.

What is the CVSS score for CVE-2023-36844?

CVE-2023-36844 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

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