CVE-2026-33672

Workarounds

If upgrading is not immediately possible, avoid passing untrusted glob patterns to picomatch.

Possible mitigations include:

• Sanitizing or rejecting untrusted glob patterns, especially those containing POSIX character classes like [[:...:]].

• Avoiding the use of POSIX bracket expressions if user input is involved.

• Manually patching the library by modifying POSIX_REGEX_SOURCE to use a null prototype:

  const POSIX_REGEX_SOURCE = {
    __proto__: null,
    alnum: 'a-zA-Z0-9',
    alpha: 'a-zA-Z',
    // ... rest unchanged
  };
  

Resources

• fix for similar issue: https://github.com/micromatch/picomatch/pull/144
• picomatch repository https://github.com/micromatch/picomatch

picomatch is vulnerable to a method injection vulnerability (CWE-1321) affecting the POSIX_REGEX_SOURCE object. Because the object inherits from Object.prototype, specially crafted POSIX bracket expressions (e.g., [[:constructor:]]) can reference inherited method names. These methods are implicitly converted to strings and injected into the generated regular expression.

This leads to incorrect glob matching behavior (integrity impact), where patterns may match unintended filenames. The issue does not enable remote code execution, but it can cause security-relevant logic errors in applications that rely on glob matching for filtering, validation, or access control.

All users of affected picomatch versions that process untrusted or user-controlled glob patterns are potentially impacted.

CVE-2026-33672 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.0.4, 3.0.2, 2.3.2); upgrading removes the vulnerable code path.

Kodem intelligence

This issue is fixed in picomatch 4.0.4, 3.0.2 and 2.3.2.

Users should upgrade to one of these versions or later, depending on their supported release line.

1. What is CVE-2026-33672? CVE-2026-33672 is a medium-severity security vulnerability in picomatch (npm), affecting versions >= 4.0.0, < 4.0.4. It is fixed in 4.0.4, 3.0.2, 2.3.2.
2. How severe is CVE-2026-33672? CVE-2026-33672 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of picomatch are affected by CVE-2026-33672? picomatch (npm) versions >= 4.0.0, < 4.0.4 is affected.
4. Is there a fix for CVE-2026-33672? Yes. CVE-2026-33672 is fixed in 4.0.4, 3.0.2, 2.3.2. Upgrade to this version or later.
5. Is CVE-2026-33672 exploitable, and should I be worried? Whether CVE-2026-33672 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-33672 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-33672?
   • Upgrade picomatch to 4.0.4 or later
   • Upgrade picomatch to 3.0.2 or later
   • Upgrade picomatch to 2.3.2 or later