# CVE-2026-33672: Picomatch: Method Injection in POSIX Character Classes causes incorrect Glob Matching > Attackers can inject inherited methods into regex via POSIX classes, causing incorrect glob matching and potential security bypasses in applications using picomatch. - **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 26 Mar 2026 - **Updated:** 27 Mar 2026 - **Also known as:** AZL-81023, AZL-81038, CLEANSTART-2026-LA61588, CLEANSTART-2026-LU58636, CLEANSTART-2026-RI19788, CLEANSTART-2026-SS22483, DEBIAN-CVE-2026-33672, GHSA-3v7f-55p6-f55p, MINI-38qq-mc2c-m529, MINI-3xg3-8935-8gx9, MINI-4hc2-x7wv-452p, MINI-52w5-xp2q-96w2, MINI-5c4r-6mwm-pcpm, MINI-6hrg-c9pf-3mpp, MINI-6jgv-6j52-hq2h, MINI-76qx-24gc-g3v2, MINI-78h7-9vx2-8v42, MINI-7mjv-4327-52hm, MINI-7v7x-9xvj-mg4x, MINI-87x9-pwj2-cmh8, MINI-89j2-6v95-jh73, MINI-9j4f-68fw-mr3h, MINI-cqrh-j9cr-2rc3, MINI-fhrq-87jf-ggr5, MINI-hch4-44c6-cppr, MINI-hgxx-73vp-j8p6, MINI-hq85-5jg4-88xh, MINI-j9fc-gp87-p4hf, MINI-p5rp-m5fx-h77r, MINI-pmh9-pcr6-rc8p, MINI-r7j2-4p32-g44g, MINI-rxhp-p65x-c94p, MINI-rxrp-3gr5-r6wp, MINI-v5x3-gjcc-hxmq, MINI-wmfh-rm4p-vgff, MINI-xjvc-fvw5-33wm, ROOT-APP-NPM-CVE-2026-33672, UBUNTU-CVE-2026-33672 ## What is CVE-2026-33672? CVE-2026-33672 is a medium-severity code injection vulnerability in micromatch picomatch, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Picomatch is a glob matcher written JavaScript. Versions prior to 4.0.4, 3.0.2, and 2.3.2 are vulnerable to a method injection vulnerability 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. 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. 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; and manually patching the library by modifying `POSIX_REGEX_SOURCE` to use a null prototype. Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes) ## Which versions are affected by CVE-2026-33672? 6 open source packages ship an affected version, including picomatch. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `picomatch` | npm | All versions | 2.3.2 | | `picomatch` | npm | All versions | 2.3.2 | | `picomatch` | npm | From 3.0.0 | 3.0.2 | | `picomatch` | npm | From 3.0.0 | 3.0.2 | | `picomatch` | npm | From 4.0.0 | 4.0.4 | | `picomatch` | npm | From 4.0.0 | 4.0.4 | Products: Jonschlinkert Picomatch. ## How do I fix CVE-2026-33672? Upgrade picomatch to a fixed version for your release line: 2.3.2, 3.0.2 or 4.0.4. ## Is CVE-2026-33672 being exploited? There is no known exploitation of CVE-2026-33672 in the wild and no public exploit code. ## Other vulnerabilities in micromatch picomatch - [CVE-2026-33671](https://insights.sbomify.com/CVE-2026-33671/): Picomatch has a ReDoS vulnerability via extglob quantifiers (high 7.5) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-33672 and fix it if it is affected. What it is: CVE-2026-33672 is a medium-severity code injection vulnerability in micromatch picomatch, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-33672 in the wild and no public exploit code. Affected packages and fixed versions: - picomatch (npm): affected all versions; fixed in 2.3.2 - picomatch (npm): affected all versions; fixed in 2.3.2 - picomatch (npm): affected from 3.0.0; fixed in 3.0.2 - picomatch (npm): affected from 3.0.0; fixed in 3.0.2 - picomatch (npm): affected from 4.0.0; fixed in 4.0.4 - picomatch (npm): affected from 4.0.0; fixed in 4.0.4 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-33672/ (Markdown: https://insights.sbomify.com/CVE-2026-33672/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33672 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33672 - OSV: https://osv.dev/vulnerability/CVE-2026-33672 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-33672/ Summaries are generated and may contain mistakes; the official description above is the record.