CVE-2023-39238Network attack vector

Remote code execution via unvalidated format string

Published Sep 7, 2023 · Updated Sep 26, 2024

Format string injection in ASUS RT-AX55 and RT-AX56U V2 firmware 3.0.0.4.386_50460 allows remote authenticated users to execute code. The set_iperf3_svr.cgi API in the iperf module accepts a user-controlled formatting value without validating it before using it as a format string. Administrative router access is required; successful exploitation permits arbitrary device operations or a service interruption.

CVSS severity7.2
High
EPSS probability1.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Format string injection in ASUS RT-AX55 and RT-AX56U V2 firmware 3.0.0.4.386_50460 allows remote authenticated users to execute code. The set_iperf3_svr.cgi API in the iperf module accepts a user-controlled formatting value without validating it before using it as a format string. Administrative router access is required; successful exploitation permits arbitrary device operations or a service interruption.

The record

CVE
CVE-2023-39238
Published
Sep 7, 2023
Updated
Sep 26, 2024
Vendor
ASUSTeK Computer Inc.
Product
RT-AX55
Classifications
CWE-134, CAPEC-135, T1210
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Sep 7, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 26, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.0.0.4.386_50460

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

ASUSTeK Computer Inc. · RT-AX55version=3.0.0.4.386_50460
ASUSTeK Computer Inc. · RT-AX56U V2version=3.0.0.4.386_50460

Published CVSS scores

7.2TWCERT/CCCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-134Use of Externally-Controlled Format String
CAPEC-135Format String Injection
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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