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CVE-2023-36844

Juniper Junos OS EX Series PHP External Variable Modification

5.3 MEDIUMActively exploited (CISA KEV)Public exploitEPSS 90.0%
  1. Published17 Aug 2023
  2. Added to CISA KEV13 Nov 2023
  3. Remediation due17 Nov 2023
Actively exploited (CISA KEV)

Juniper Junos OS on EX Series contains a PHP external variable modification vulnerability that 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.

Added to KEV: 13 Nov 2023Federal remediation due: 17 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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

Juniper Junos< 20.4 · 20.4 · 21.1 · 21.2

Remediation

Fixed in
Juniper Junos≥ 20.4

References

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Frequently asked

Is CVE-2023-36844 being actively exploited?

Yes. CVE-2023-36844 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 13 Nov 2023.

How severe is CVE-2023-36844?

CVE-2023-36844 has a CVSS 3.1 base score of 5.3, rated medium. EPSS estimates a 90.0% probability of exploitation.

Which products are affected by CVE-2023-36844?

Affected products include Juniper Junos.

How do I fix CVE-2023-36844?

Upgrade affected software to a fixed version, for example Juniper Junos 20.4 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2023-36844 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.