CVE-2023-35086
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIt is identified a format string vulnerability in ASUS RT-AX56U V2 & RT-AC86U. This vulnerability is caused by directly using input as a format string when calling syslog in logmessage_normal function, in the do_detwan_cgi module of httpd. A remote attacker with administrator privilege can exploit this vulnerability to perform remote arbitrary code execution, arbitrary system operation or disrupt service. This issue affects RT-AX56U V2: 3.0.0.4.386_50460; RT-AC86U: 3.0.0.4_386_51529.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceFormat string vulnerability in ASUS RT-AX56U V2 and RT-AC86U routers where the logmessage_normal function in the do_detwan_cgi module of httpd directly uses attacker-supplied input as a format string in syslog calls. A remote attacker with administrator privileges can exploit this to achieve remote code execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 3.0.0.4_386_51529= 3.0.0.4.386_50460CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify router modelCheck the device label or web interface to confirm the exact model is ASUS RT-AC86U or RT-AX56U V2Affected if Model is RT-AC86U or RT-AX56U V2
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Check installed firmware versionAccess router web interface (usually 192.168.1.1), navigate to Administration > Firmware Upgrade or similar, or run 'nvram get firmware_version' via telnet/SSH if availableAffected if Firmware version is 3.0.0.4_386_51529 (for RT-AC86U) or 3.0.0.4.386_50460 (for RT-AX56U V2)
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Verify httpd service is runningCheck if the router web interface (httpd) is accessible on the WAN interface by accessing the router's public IP on ports 80/443Affected if httpd is exposed and accessible from the network
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Check if remote administrative access is enabledIn router web interface, go to Administration > System > Enable Web GUI from WAN, or check firewall rules that allow external access to ports 80/443Affected if Remote administrative access is enabled and the httpd is reachable from the internet
You are affected if you have an RT-AC86U or RT-AX56U V2 router running exactly firmware version 3.0.0.4_386_51529 or 3.0.0.4.386_50460 respectively, and the httpd service is accessible to an attacker with admin privileges.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply ASUS vendor firmware updates when released. Restrict administrative web interface access to trusted IP addresses only until patch is available.
- Consultation3.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,832.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-35086 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-35086 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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