What is CWE-749?
The product provides an Applications Programming Interface (API) or similar interface for interaction with external actors, but the interface includes a dangerous method or function that is not properly restricted.
This weakness can lead to a wide variety of resultant weaknesses, depending on the behavior of the exposed method. It can apply to any number of technologies and approaches, such as ActiveX controls, Java functions, IOCTLs, and so on. The exposure can occur in a few different ways: The function/method was never intended to be exposed to outside actors. The function/method was only intended to be accessible to a limited set of actors, such as Internet-based access from a single web site.
CWE-749 is a base-level weakness in MITRE’s Common Weakness Enumeration, with a MITRE likelihood of exploit of Low. Applicable platforms: Language: Not Language-Specific.
Source: MITRE CWE (CWE-749 definition, reproduced verbatim). Counts and linkage below are Threadlinqs data.
Consequences
- Integrity, Confidentiality, Availability, Access Control, Other — Gain Privileges or Assume Identity, Read Application Data, Modify Application Data, Execute Unauthorized Code or Commands, Other. Exposing critical functionality essentially provides an attacker with the privilege level of the exposed functionality. This could result in the modification or exposure of sensitive data or possibly even execution of arbitrary code.
Source: MITRE CWE, common consequences.
How CWE-749 is exploited in the wild
Threadlinqs maps 3 CVEs to CWE-749, published between 2026-08-06 and 2026-09-08. None of them is in the CISA KEV catalog yet. By CVSS v3 severity the set splits into 1 critical, 2 high. The highest EPSS score in the set is 0.9% (CVE-2026-68823), the modelled probability of exploitation in the next 30 days. 11 tracked threats reference CWE-749 directly or through a CVE it covers; the most recent is “Eclypsium InfraTrust Report: Mass Active Exploitation of Network Management Systems (Cisco FMC/ISE CVE-2026-20079, CVE-2026-76460; SonicWall SMA 1000 CVE-2026-83548/83549; Linux Kernel CopyFail CVE-2026-31431)” (2026-09-23). Affected products concentrate in Cisco (1), Microsoft (1), truelockmc (1).
Vulnerabilities (CVEs)
All 3 CVEs mapped to CWE-749, CISA KEV first, then by CVSS score.
- CVE-2026-68823 — CVSS 9.1 critical · EPSS 0.9% · published 2026-08-06
- CVE-2026-52877 — CVSS 8.3 high · EPSS 0.3% · published 2026-08-18
- CVE-2026-20293 — CVSS 7.1 high · EPSS 0.1% · published 2026-09-08
Affected vendors
Threat activity
11 tracked threats cite CWE-749:
- Eclypsium InfraTrust Report: Mass Active Exploitation of Network Management Systems (Cisco FMC/ISE CVE-2026-20079, CVE-2026-76460; SonicWall SMA 1000 CVE-2026-83548/83549; Linux Kernel CopyFail CVE-2026-31431)CRITICAL
- Microsoft August 2026 Patch Tuesday: 400 Flaws Fixed, Including Lazarus-Exploited Zero-Day CVE-2026-68820 (AFD.sys) and Two Publicly Disclosed Zero-Days (CVE-2026-62832 "LegacyHive", CVE-2026-72971)CRITICAL
- GentleKiller BYOVD EDR-Killing Framework Operated by The Gentlemen RaaS (hastalamuerte / Qilin lineage)HIGH
- Exposed RDP / RDWeb Misconfigurations Exploited for Initial Access and Lateral Movement (Huntress 2026)HIGH
- Internet Explorer WebBrowser Control Attack Chain — Two-Click RCE via Zone/MOTW Bypass and ActiveX COM (Positive Technologies)HIGH
- Operation FlutterBridge — FlutterShell macOS Backdoor via Malicious Google/YouTube Ads (CL-CRI-1089)HIGH
- BTMOB Android RAT — SpySolr Evolution Sold as MaaS via Telegram with APK Builder and Accessibility Services AbuseHIGH
- Weaver E-cology Unauthenticated RCE (CVE-2026-22679) — Active Exploitation Since Mid-March 2026 via dubboApi Debug EndpointCRITICAL
- 108 Malicious Chrome Extensions Share C2 Infrastructure for Session Cookie Theft and Browser Data ExfiltrationHIGH
- React2Shell CVE-2025-55182 — Multiple Threat Actors Actively Exploiting React Server Components RCE (CVSS 10.0)CRITICAL
- LLMJacking: 175,000 Exposed Ollama AI Servers Targeted for AbuseHIGH
Mitigations
- Architecture and Design: If you must expose a method, make sure to perform input validation on all arguments, limit access to authorized parties, and protect against all possible vulnerabilities.
- Architecture and Design, Implementation / Attack Surface Reduction: Identify all exposed functionality. Explicitly list all functionality that must be exposed to some user or set of users. Identify which functionality may be: accessible to all users restricted to a small set of privileged users prevented from being directly accessible at all Ensure that the implemented code follows these expectations. This includes setting the appropriate access modifiers where applicable (public, private, protected, etc.) or not marking ActiveX controls safe-for-scripting.
Source: MITRE CWE, potential mitigations.
Detection methods (MITRE CWE)
- 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.