GHSA-3v7f-55p6-f55p is a medium-severity (CVSS 5.3) CWE-1321 vulnerability in picomatch. O3 Security confirms whether GHSA-3v7f-55p6-f55p is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Picomatch: Method Injection in POSIX Character Classes causes incorrect Glob Matching
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-3v7f-55p6-f55p.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
picomatchnpmDescription
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_SOURCEto 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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | picomatch | ≥ 4.0.0&&< 4.0.4 | 4.0.4 |
| 📦npm | picomatch | ≥ 3.0.0&&< 3.0.2 | 3.0.2 |
| 📦npm | picomatch | all versions | 2.3.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for picomatch. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update picomatch to 4.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3v7f-55p6-f55p is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-3v7f-55p6-f55p is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-3v7f-55p6-f55p. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-3v7f-55p6-f55p in your dependencies?
O3 detects GHSA-3v7f-55p6-f55p across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.