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CVE-2023-36844

Junos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variables

  • Medium 5.3
  • Exploited: added to CISA KEV 13 Nov 2023

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.

Key facts

Published
17 Aug 2023
Last changed
21 Oct 2025
Assigned by
juniper
KEV added
13 Nov 2023
KEV fix due
17 Nov 2023
EPSS
89.958% likely to be exploited in the next 30 days, higher than 99.797% of CVEs (scores for 15 Nov 2026)
SSVC (CISA)
Exploitation: active; Automatable: yes; Technical impact: total

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

  • 5.3CVSS 3.1, Mediumfrom the CNA (juniper)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

What to do

  • The following software releases have been updated to resolve this specific issue: 20.4R3-S9*, 21.2R3-S7*, 21.3R3-S5*, 21.4R3-S5*, 22.1R3-S4*, 22.2R3-S2, 22.3R3-S1*, 22.4R2-S2*, 22.4R3*, 23.2R1-S1, 23.2R2*, 23.4R1*, and all subsequent releases. *Pending PublicationCNA solution statement
  • Disable J-Web, or limit access to only trusted hosts.CNA workaround statement
  • Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.CISA KEV required action

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

VendorProductVersions
Juniper NetworksJunos OS
  • Default status: unaffected
  • 0 up to but excluding 20.4R3-S9 (affected)
  • 21.1 up to but excluding 21.1* (affected)
  • 21.2 up to but excluding 21.2R3-S6 (affected)
  • 21.3 up to but excluding 21.3R3-S5 (affected)
  • 21.4 up to but excluding 21.4R3-S5 (affected)
  • 22.1 up to but excluding 22.1R3-S4 (affected)
  • 22.2 up to but excluding 22.2R3-S2 (affected)
  • 22.3 up to but excluding 22.3R3-S1 (affected)
  • 22.4 up to but excluding 22.4R2-S2, 22.4R3 (affected)
  • 23.2 up to but excluding 23.2R1-S1, 23.2R2 (affected)

Timeline

  1. 17 Aug 2023 Published
  2. 13 Nov 2023 CVE-2023-36844 added to CISA KEV
  3. 13 Nov 2023 Added to the CISA KEV catalogue

Weakness

References