CVE-2023-40507: High XXE Data Leak in LG Simple Editor

CVE-2023-40507 is a high flaw in LG Simple Editor 3.21.0: the copyContent method has a XML external entity bug that discloses information. NVD scores it 7.5 (High). LG told the Zero Day Initiative it will not fix it, so no patch exists. Restrict access to the application or remove it.

What's affected

The record lists one product and one version: LG Simple Editor 3.21.0 (the CPE vendor field reads lg). The weakness class is CWE-611.

The vulnerable code is the copyContent method, which restricts XML external entity references improperly, so a crafted document that names a URI makes the parser fetch it and embed the result for further processing. Because the process runs as SYSTEM, the content that could be fetched is not limited to the application's own data, and the record scores confidentiality as high with no integrity or availability impact.

No fixed version exists. The Zero Day Initiative advisory ZDI-23-1211 (tracked as ZDI-CAN-20006) says ZDI reported the issue to LG on 14 February 2023. On 8 August 2023 the vendor stated it does not plan to fix it now or in the future. ZDI then published it as a zero day advisory on 24 August 2023. NVD added the record on 3 May 2024. The record does not say whether versions other than 3.21.0 are affected, and the advisory names no safe version.

It is not in CISA's Known Exploited Vulnerabilities catalog, and the advisory does not say it is exploited in the wild.

How to check if you're exposed

There is no package feed to scan for this one, so exposure comes down to whether the application is installed and reachable. The record lists no authentication requirement, so network reachability is the only barrier.

On a Windows host, check whether LG Simple Editor is installed and which version:

Get-Package | Where-Object Name -like "*Simple Editor*"

Also look in Apps and features, because not every installer registers with that command. Then list listening sockets and match the owning process to the application:

netstat -ano | findstr LISTENING
tasklist /FI "PID eq 1234"

Replace 1234 with a process ID from the first command. If you find version 3.21.0 and the service answers from any network other than a trusted administration segment, treat the host as exposed. Add the host to your software inventory either way, so a later fix notice from LG reaches someone who can act on it.

What to do now

1. Inventory every host that has LG Simple Editor installed and record the version.
2. Remove network access you do not need. Block inbound connections to the service at the host firewall and the perimeter, and allow only named administrators.
3. If the product is not in active use, uninstall it. With no vendor fix, retirement is the only complete remedy.
4. Watch for outbound requests from the host to internal or unusual addresses, and for requests to this endpoint from unexpected sources.
5. Ask LG whether a patched version or a replacement exists, and recheck the Zero Day Initiative advisory for updates.

Why it matters

XML allows documents to define entities that point at external resources. If a parser resolves them for input it did not author, a document can make the server read a local file or request an internal address and return the result. Turning off external entity and DTD processing in the parser is the standard defense, and it needs a change in the vendor's code.

The advisory says the contents are embedded back into the document for further processing, which is why the record treats this as disclosure. The vector shows no impact on integrity or availability. The vendor has said it will not patch this, which is the main reason the guidance here is about reducing exposure.

This is one of many records filed against LG Simple Editor 3.21.0 from the same ZDI batch, each tied to a different method. Each bug stands alone, so the safest reading is that the product as a whole should stay off untrusted networks.

Quick check

Sources

• Zero Day Initiative advisory ZDI-23-1211
• Safeguard Gold entry for CVE-2023-40507
• NVD record for CVE-2023-40507, as supplied in the Safeguard CVE dataset

Last reviewed: 19 October 2026.