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Weakness · BaseCWE-494

CWE-494: Download of Code Without Integrity Check

Likelihood of exploit: MediumKEV-linkedBase

As of 2026-10-05, CWE-494 (Download of Code Without Integrity Check) underlies 5 CVEs tracked by Threadlinqs, 2 of them in the CISA Known Exploited Vulnerabilities catalog, and is cited by 247 tracked threats. MITRE rates its likelihood of exploit as Medium.

CVEs
5Mapped to CWE-494
CISA KEV
2Exploited in the wild
Critical
0CVSS v3 critical CVEs
Threats
247Tracked campaigns citing it
Likelihood
MediumMITRE likelihood of exploit

Last updated:

What is CWE-494?

The product downloads source code or an executable from a remote location and executes the code without sufficiently verifying the origin and integrity of the code.

An attacker can execute malicious code by compromising the host server, performing DNS spoofing, or modifying the code in transit.

CWE-494 is a base-level weakness in MITRE’s Common Weakness Enumeration, with a MITRE likelihood of exploit of Medium. Applicable platforms: Language: Not Language-Specific.

Source: MITRE CWE (CWE-494 definition, reproduced verbatim). Counts and linkage below are Threadlinqs data.

Consequences

  • Integrity, Availability, Confidentiality, Other — Execute Unauthorized Code or Commands, Alter Execution Logic, Other. Executing untrusted code could compromise the control flow of the program. The untrusted code could execute attacker-controlled commands, read or modify sensitive resources, or prevent the software from functioning correctly for legitimate users.

Source: MITRE CWE, common consequences.

How CWE-494 is exploited in the wild

Threadlinqs maps 5 CVEs to CWE-494, published between 2026-01-07 and 2026-08-25. 2 are listed in CISA’s Known Exploited Vulnerabilities catalog, the authoritative record of exploitation in the wild. By CVSS v3 severity the set splits into 4 high. The highest EPSS score in the set is 5.3% (CVE-2025-15556), the modelled probability of exploitation in the next 30 days. 247 tracked threats reference CWE-494 directly or through a CVE it covers; the most recent is “Adform Ad-Tech Platform Compromised: Trojanized Tracking Script Serves Crypto Clipboard Stealer via Supply-Chain Attack” (2026-09-26). Affected products concentrate in ConnectWise (1), Notepad-plus-plus (1), Pnpm (1), among 5 vendors in total.

Vulnerabilities (CVEs)

All 5 CVEs mapped to CWE-494, CISA KEV first, then by CVSS score.

  • CVE-2026-3502 — CISA KEV · CVSS 7.8 high · EPSS 1.4% · published 2026-03-30
  • CVE-2025-15556 — CISA KEV · CVSS 7.5 high · EPSS 5.3% · published 2026-02-03
  • CVE-2026-9089 — CVSS 8.8 high · EPSS 0.0% · published 2026-05-21
  • CVE-2025-69263 — CVSS 7.5 high · EPSS 0.0% · published 2026-01-07
  • CVE-2026-57910 — EPSS 0.1% · published 2026-08-25

Affected vendors

Threat activity

247 tracked threats cite CWE-494; the 25 most recent are listed.

Mitigations

  • Implementation: Perform proper forward and reverse DNS lookups to detect DNS spoofing.
  • Architecture and Design, Operation: Encrypt the code with a reliable encryption scheme before transmitting. This will only be a partial solution, since it will not detect DNS spoofing and it will not prevent your code from being modified on the hosting site.
  • Architecture and Design / Libraries or Frameworks: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482]. Speficially, it may be helpful to use tools or frameworks to perform integrity checking on the transmitted code. When providing the code that is to be downloaded, such as for automatic updates of the software, then use cryptographic signatures for the code and modify the download clients to verify the signatures. Ensure that the implementation does not contain CWE-295, CWE-320, CWE-347, and related weaknesses. Use code signing technologies such as Authenticode. See references [REF-454] [REF-455] [REF-456].
  • Architecture and Design, Operation / Environment Hardening: Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
  • Architecture and Design, Operation / Sandbox or Jail: 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…

Source: MITRE CWE, potential mitigations.

Detection methods (MITRE CWE)

  • Manual Analysis: This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. Specifically, manual static analysis is typically required to find the behavior that triggers the download of code, and to determine whether integrity-checking methods are in use.
  • Black Box: Use monitoring tools that examine the software's process as it interacts with the operating system and the network. This technique is useful in cases when source code is unavailable, if the software was not developed by you, or if you want to verify that the build phase did not introduce any new weaknesses. Examples include debuggers that directly attach to the running process; system-call tracing utilities such as truss (Solaris) and strace (Linux); system activity monitors such as FileMon…
  • Automated Static Analysis (effectiveness: High): Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Source: MITRE CWE, detection methods. Threadlinqs detection rules for the threats above are Blue tier and higher.