CVE-2023-39240 | ASUS RT-AX55、RT-AX56U_V2 - Format String - 3

It is identified a format string vulnerability in ASUS RT-AX56U V2’s iperf client function API. This vulnerability is caused by lacking validation for a specific value within its set_iperf3_cli.cgi module. A remote attacker with administrator privilege can exploit this vulnerability to perform remote arbitrary code execution, arbitrary system operation or disrupt service.

Published: 2023-09-07 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-39240 is rated Moderate Risk (56.6/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.13%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-39240

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-02 0.85% 1.13% +0.28%
2 2025-11-21 1.48% 0.85% -0.63%
3 2025-11-18 — 1.48% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-39240

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.2 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.2 5.9 [email protected]

Weakness enumeration for CVE-2023-39240

Affected software / configurations for CVE-2023-39240

Vendor Product Version Raw CPE
asus rt-ax55_firmware 3.0.0.4.386_50460 cpe:2.3:o:asus:rt-ax55_firmware:3.0.0.4.386_50460:*:*:*:*:*:*:*
asus rt-ax56u_v2_firmware 3.0.0.4.386_50460 cpe:2.3:o:asus:rt-ax56u_v2_firmware:3.0.0.4.386_50460:*:*:*:*:*:*:*
asus rt-ac86u_firmware 3.0.0.4_386_51529 cpe:2.3:o:asus:rt-ac86u_firmware:3.0.0.4_386_51529:*:*:*:*:*:*:*

References for CVE-2023-39240

cvelogic Threat Intelligence