CVE-2026-33672 is a medium-severity (CVSS 5.3) CWE-1321 vulnerability in picomatch. A fix is available for picomatch — see the affected versions and patch details below.
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 CVE-2026-33672.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-33672 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 | 4.0.4npm install picomatch@4.0.4 |
| 📦npm | picomatch | ≥ 3.0.0&&< 3.0.2 | 3.0.2npm install picomatch@3.0.2 |
| 📦npm | picomatch | all versions | 2.3.2npm install picomatch@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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update picomatch to 4.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33672 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33672 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33672. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Openshift Data Foundation 4.18 | odf4/cephcsi-rhel9:1786705347 | RHSA-2026:56431 |
| Red Hat Openshift Data Foundation 4.22 | odf4/cephcsi-rhel9:1787057250 | RHSA-2026:56928 |
Frequently Asked Questions
Is CVE-2026-33672 in your dependencies?
O3 Security finds CVE-2026-33672 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.