Update dependency picomatch to v4.0.4 [SECURITY]

[matticbot]

This PR contains the following updates:

Package	Change	Age	Confidence
picomatch	4.0.2 → 4.0.4

GitHub Vulnerability Alerts

CVE-2026-33671

Impact

picomatch is vulnerable to Regular Expression Denial of Service (ReDoS) when processing crafted extglob patterns. Certain patterns using extglob quantifiers such as +() and *(), especially when combined with overlapping alternatives or nested extglobs, are compiled into regular expressions that can exhibit catastrophic backtracking on non-matching input.

Examples of problematic patterns include +(a|aa), +(*|?), +(+(a)), *(+(a)), and +(+(+(a))). In local reproduction, these patterns caused multi-second event-loop blocking with relatively short inputs. For example, +(a|aa) compiled to ^(?:(?=.)(?:a|aa)+)$ and took about 2 seconds to reject a 41-character non-matching input, while nested patterns such as +(+(a)) and *(+(a)) took around 29 seconds to reject a 33-character input on a modern M1 MacBook.

Applications are impacted when they allow untrusted users to supply glob patterns that are passed to picomatch for compilation or matching. In those cases, an attacker can cause excessive CPU consumption and block the Node.js event loop, resulting in a denial of service. Applications that only use trusted, developer-controlled glob patterns are much less likely to be exposed in a security-relevant way.

Patches

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.

Workarounds

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

Possible mitigations include:

• disable extglob support for untrusted patterns by using noextglob: true
• reject or sanitize patterns containing nested extglobs or extglob quantifiers such as +() and *()
• enforce strict allowlists for accepted pattern syntax
• run matching in an isolated worker or separate process with time and resource limits
• apply application-level request throttling and input validation for any endpoint that accepts glob patterns

Resources

• Picomatch repository: https://github.com/micromatch/picomatch
• lib/parse.js and lib/constants.js are involved in generating the vulnerable regex forms
• Comparable ReDoS precedent: CVE-2024-4067 (micromatch)
• Comparable generated-regex precedent: CVE-2024-45296 (path-to-regexp)

CVE-2026-33672

Impact

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.

Patches

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.

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

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Release Notes

micromatch/picomatch (picomatch)

v4.0.4

Compare Source

This is a security release fixing several security relevant issues.

What's Changed

• Fix for CVE-2026-33671
• Fix for CVE-2026-33672

Full Changelog: micromatch/picomatch@4.0.3...4.0.4

v4.0.3

Compare Source

What's Changed

• fix: exception when glob pattern contains constructor by @​Jason3S in #​144

New Contributors

• @​Jason3S made their first contribution in #​144

Full Changelog: micromatch/picomatch@4.0.2...4.0.3

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[github-actions]

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[tbradsha]

Should be fine if CI is happy.

[jp-launch-control]

Code Coverage Summary

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