CVE-2026-4255

NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-4255
CWE	https://cwe.mitre.org/data/definitions/829.html

A DLL search order hijacking vulnerability in Thermalright TR-VISION HOME on Windows (64-bit) allows a local attacker to escalate privileges via DLL side-loading. The application loads certain dynamic-link library (DLL) dependencies using the default Windows search order, which includes directories that may be writable by non-privileged users.nnnnBecause these directories can be modified by unprivileged users, an attacker can place a malicious DLL with the same name as a legitimate dependency in a directory that is searched before trusted system locations. When the application is executed, which is always with administrative privileges, the malicious DLL is loaded instead of the legitimate library.nnnnThe application does not enforce restrictions on DLL loading locations and does not verify the integrity or digital signature of loaded libraries. As a result, attacker-controlled code may be executed within the security context of the application, allowing arbitrary code execution with elevated privileges.nnnnSuccessful exploitation requires that an attacker place a crafted malicious DLL in a user-writable directory that is included in the applications DLL search path and then cause the affected application to be executed. Once loaded, the malicious DLL runs with the same privileges as the application.nnnnThis issue affects nTR-VISION HOME versions up to and including 2.0.5.

Weakness

The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.

Potential Mitigations

When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
For example, ID 1 could map to “inbox.txt” and ID 2 could map to “profile.txt”. Features such as the ESAPI AccessReferenceMap [REF-45] provide this capability.
Run the code in a “jail” or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
Be careful to avoid CWE-243 and other weaknesses related to jails.
Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single “.” character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as “/” to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering “/” is insufficient protection if the filesystem also supports the use of “" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if “../” sequences are removed from the “…/…//” string in a sequential fashion, two instances of “../” would be removed from the original string, but the remaining characters would still form the “../” string.
Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server’s access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Many file inclusion problems occur because the programmer assumed that certain inputs could not be modified, especially for cookies and URL components.

References

https://www.thermalright.com/support/download/

Inclusion of Functionality from Untrusted Control Sphere

Weakness

Potential Mitigations

Related Attack Patterns

References