studies on bugs in extensions/plugins

We have done several studies on bugs in extensions/plugins:

Each study included around 20 real-world cases, documenting common patterns, impacts, statistics, and root causes.

Summary of Findings Across Extension Ecosystems

1. Diverse Extension Environments, Similar Vulnerabilities

Despite targeting different host platforms—browsers and IDEs, database and web server engines, and hypervisor/container orchestration—the extension or plugin model consistently introduces comparable classes of bugs. In all three domains, extensions/plugins often run with broad privileges, interact with untrusted data, or integrate deeply with the host application’s internals. As a result, logic flaws, memory errors, and security oversights can lead to critical vulnerabilities, including:

Remote Code Execution (RCE): Extensions that allow file manipulation, script injection, or direct system calls can be exploited to run arbitrary code. For instance, a malicious browser extension feature (e.g., rewriting scripts) or a vCenter plugin with an open file-upload endpoint directly led to RCE.
Privilege Escalation and Policy Bypass: Add-ons such as IDE plugins, Kubernetes admission controllers, or database script extensions can inadvertently grant higher privileges than intended. Multiple cases across the studies showed how logic oversights in extension permission checks enabled low-privileged or unauthenticated attackers to escalate privileges, bypass security policies, or hijack sensitive operations.
Memory-Safety Bugs: In lower-level systems—like web server modules (Apache, Nginx), database plugins (MySQL, Redis), and hypervisor drivers (libvirt, Xen)—heap/buffer overflows, use-after-free errors, and other memory mismanagement led to crashes, data corruption, or RCE. This matches well-known industry data that memory-safety issues dominate critical vulnerabilities in C/C++ code.

2. Common Root Causes

The studies converge on several root cause patterns:

Insufficient Input Validation & Over-Trust: Many severe extension bugs arise when user, network, or project-file inputs are trusted without robust checks. For example, ad blockers injecting scripts via overly permissive filters, or a vCenter plugin failing to authenticate file uploads.
Logic and Design Oversights: Critical “bypass” vulnerabilities typically reflect flawed assumptions about state, trust boundaries, or concurrency. Cases included:
Browser/IDE: Overlooking the domain context, enabling universal XSS, reusing credentials in the wrong context.
Database/Web Servers: Mishandling extension scripts or module commands, leading to injection or privilege confusion.
Hypervisor/Containers: Race conditions in policy engines (Kubernetes Gatekeeper, Falco) or incorrectly merged network policies (Cilium).
Privilege/Policy Misconfiguration: Plugins frequently have more power than necessary, so any single oversight (e.g., forgetting to enforce authentication) can grant an attacker host-level capabilities. This was evident in multiple VMware plugin vulnerabilities, Docker authorization bypasses, and Cilium’s network policy errors.
Resource and Concurrency Bugs: Memory leaks, infinite loops, or concurrency issues (like race conditions) were found in all three sets—some triggered denial-of-service, others silently broke functionality (e.g., memory exhaustion in Xen’s XAPI or a crash loop in an IDE plugin).

3. Impacts on Security, Stability, and Maintainability

High-Severity Security Risks: Across all three studies, 60–80% of documented bugs had direct security implications, often scoring high CVSS (8.0–9.8). The biggest danger is that many extensions run in-process with high privileges, so a vulnerability can compromise the entire host.
Performance Degradation and Crashes: Non-security bugs—like memory leaks or infinite retry loops—commonly drained CPU/RAM, causing host slowdowns, browser/IDE hang-ups, or cluster-wide outages (e.g., a malicious request crashing Nginx or a cunningly crafted storage pool definition bringing down libvirt).
Data Leakage and Integrity Failures: Several bugs resulted in unauthorized disclosure of credentials (e.g., token leaks in LastPass, JetBrains GitHub plugin, or Cilium debug logs) or potential data corruption in databases.
Compatibility and Deployment Headaches: Extensions complicate upgrades and maintenance. For instance, some IDE or database upgrades failed because an extension was not updated in tandem, forcing manual or emergency patching. Meanwhile, ephemeral container or hypervisor add-ons (plugins or drivers) that are misconfigured can cause repeated crash loops or require significant debugging time.

4. Statistical Observations

Although the three studies examine different ecosystems, the breakdown of bugs is strikingly similar:

Security vs. General Bugs: The majority of publicly reported extension bugs are security-focused (roughly 60–80%), especially those with CVE identifiers. In real-world usage, performance/logic issues are also widespread but often appear in bug trackers rather than official advisories.
Frequent Bug Types:
Logic errors (policy bypasses, injection) are widespread in both high-level (JavaScript-based browser/IDE) and lower-level (C-based webserver/database) extensions.
Memory corruption is more prevalent in database/web server or hypervisor extension code, since they typically use native languages for performance.
Infinite loops, memory leaks, concurrency races occur across all extension ecosystems, from IDE plug-ins in Java to container policy controllers in Go.
Severity: About 25–30% of the bugs across each dataset are “critical” or “high” severity (RCE, major privilege escalation, or complete denial-of-service). Another 30–40% are medium severity (like partial policy bypass, token leaks, or major memory bloat). The remainder involve lower-impact or narrower-scope issues.
Root Cause: Over 90% of the severe security bugs arise from logic/design flaws or input validation issues—rather than classic memory corruption alone. Nonetheless, memory-safety errors remain a leading cause of the worst (RCE) vulnerabilities in native-code extensions.

5. Lessons and Recommendations

Extension Hardening & Privilege Isolation: Because a single extension flaw can compromise the entire system, vendors and administrators should isolate or sandbox plugin code where feasible, minimizing what an extension can access. This is especially critical in virtualization (VMware, Xen, Docker) and enterprise (IDE, DB) contexts.
Robust Secure Coding Practices: For memory-heavy or native-code plugins, strict memory-safety measures, fuzz testing, and code review are essential to prevent buffer overflows or use-after-free. For higher-level extensions, carefully validate untrusted inputs and domain contexts.
Regular Audits & Fast Patch Cycles: Extension ecosystems demand rapid patch deployment, especially for widely used components. The studies show a pattern of “emergency patches,” sometimes within days, to fix critical extension bugs. Maintaining a structured vulnerability disclosure and update mechanism is key.
Monitor for Regressions: The Docker AuthZ bypass recurred due to a regression in code that had been previously patched. Relying on comprehensive regression tests—particularly around security-critical logic—can prevent reintroducing old flaws.
Secure Defaults & Minimal Plugin Usage: Both end-users and platform vendors can reduce risk by installing only necessary extensions, ensuring secure defaults, and enforcing principle of least privilege.

Conclusion

Across browser/IDE, database/webserver, and hypervisor/container ecosystems, extensions expand functionality but also broaden the attack surface and failure modes. The collected bug studies reveal consistent patterns: logic flaws, missing validations, and memory-safety mistakes can yield remote compromise, data leaks, or system crashes. Many vulnerabilities manifest at high severity—RCE or privilege escalation—since plugins often run with access to the host’s most sensitive operations.

To mitigate these risks, maintainers and developers must apply rigorous security engineering to extensions as thoroughly as they do to core systems. This includes adopting safer coding practices (memory safety, validated inputs), systematically restricting plugin privileges, providing timely patches, and continuously auditing for newly introduced or regressed vulnerabilities. By following these guidelines, organizations can enjoy the benefits of extensibility while minimizing the associated security and reliability pitfalls.

Share on Share on