CVE-2023-36845
Published: 17 August 2023
Summary
CVE-2023-36845 is a critical-severity PHP External Variable Modification (CWE-473) vulnerability in Juniper Junos. Its CVSS base score is 9.8 (Critical).
Operationally, ranked in the top 0.0% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and SI-10 (Information Input Validation).
Deeper analysis
CVE-2023-36845 is a PHP External Variable Modification vulnerability in the J-Web interface of Juniper Networks Junos OS on EX Series and SRX Series platforms. An unauthenticated network attacker can supply a crafted request that sets the PHPRC variable, altering the PHP execution environment to permit injection and execution of arbitrary code. The flaw affects all versions prior to 20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S2, 22.3R2-S2/22.3R3-S1, 22.4R2-S1/22.4R3, and 23.2R1-S1/23.2R2, as well as 21.1R1 and later releases before the listed fixes.
An unauthenticated remote attacker can exploit the issue over the network to achieve full remote code execution with no user interaction or credentials required, corresponding to the CVSS 9.8 rating.
The official Juniper advisory JSA72300 directs customers to install the fixed releases enumerated above; no other workarounds are specified in the reference materials.
Public exploit code for the vulnerability has been posted to Packet Storm, and the EPSS score has reached a peak of 0.9719 with a current value of 0.9435, indicating sustained exploitation interest after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-40765
Vulnerability details
A PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series and SRX Series allows an unauthenticated, network-based attacker to remotely execute code. Using a crafted request which sets the variable PHPRC an attacker is…
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able to modify the PHP execution environment allowing the injection und execution of code. This issue affects Juniper Networks Junos OS on EX Series and SRX 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 22.3R2-S2, 22.3R3-S1; * 22.4 versions prior to 22.4R2-S1, 22.4R3; * 23.2 versions prior to 23.2R1-S1, 23.2R2.
- CWE(s)
- KEV Date Added
- 13 November 2023
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly blocks crafted requests that modify the PHPRC external variable to inject and execute arbitrary PHP code.
Enforces authentication and authorization requirements on J-Web, denying unauthenticated network attackers the ability to reach the vulnerable endpoint.
Requires prompt application of vendor patches that eliminate the PHP External Variable Modification flaw in the listed Junos releases.