GHSA-3V7F-55P6-F55P

Vulnerability from github – Published: 2026-03-25 21:13 – Updated: 2026-03-27 21:36
VLAI
Summary
Picomatch: Method Injection in POSIX Character Classes causes incorrect Glob Matching
Details

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:

```js 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
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "picomatch"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.0.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "picomatch"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "picomatch"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33672"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1321"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-25T21:13:39Z",
    "nvd_published_at": "2026-03-26T22:16:30Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\npicomatch 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.\n\nThis 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.\n\nAll users of affected `picomatch` versions that process untrusted or user-controlled glob patterns are potentially impacted.\n\n### Patches\n\nThis issue is fixed in picomatch 4.0.4, 3.0.2 and 2.3.2.\n\nUsers should upgrade to one of these versions or later, depending on their supported release line.\n\n### Workarounds\n\nIf upgrading is not immediately possible, avoid passing untrusted glob patterns to picomatch.\n\nPossible mitigations include:\n- Sanitizing or rejecting untrusted glob patterns, especially those containing POSIX character classes like `[[:...:]]`.\n- Avoiding the use of POSIX bracket expressions if user input is involved.\n- Manually patching the library by modifying `POSIX_REGEX_SOURCE` to use a null prototype:\n\n  ```js\n  const POSIX_REGEX_SOURCE = {\n    __proto__: null,\n    alnum: \u0027a-zA-Z0-9\u0027,\n    alpha: \u0027a-zA-Z\u0027,\n    // ... rest unchanged\n  };\n  \n### Resources\n\n- fix for similar issue: https://github.com/micromatch/picomatch/pull/144\n- picomatch repository https://github.com/micromatch/picomatch",
  "id": "GHSA-3v7f-55p6-f55p",
  "modified": "2026-03-27T21:36:24Z",
  "published": "2026-03-25T21:13:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/micromatch/picomatch/security/advisories/GHSA-3v7f-55p6-f55p"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33672"
    },
    {
      "type": "WEB",
      "url": "https://github.com/micromatch/picomatch/commit/4516eb521f13a46b2fe1a1d2c9ef6b20ddc0e903"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/micromatch/picomatch"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Picomatch: Method Injection in POSIX Character Classes causes incorrect Glob Matching"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.