CVE-2026-33671 is a high-severity (CVSS 7.5) CWE-1333 vulnerability in picomatch. A fix is available for picomatch — see the affected versions and patch details below.
Picomatch has a ReDoS vulnerability via extglob quantifiers
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-2026-33671.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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 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.jsandlib/constants.jsare involved in generating the vulnerable regex forms- Comparable ReDoS precedent: CVE-2024-4067 (
micromatch) - Comparable generated-regex precedent: CVE-2024-45296 (
path-to-regexp)
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 |
Affected Products
picomatchjonschlinkertDetection & 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-2026-33671 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
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.
To mitigate this issue, applications using Picomatch should avoid passing untrusted glob patterns for compilation or matching. Implementations can disable extglob support for untrusted patterns by setting `noextglob: true` in Picomatch configurations. Alternatively, reject or sanitize patterns containing nested extglobs or specific extglob quantifiers like `+()` and `*()`. Enforcing strict allowlists for accepted pattern syntax can also reduce exposure. If the application is a service, consider running the matching process in an isolated worker or separate process with time and resource limits, and apply application-level request throttling and input validation for any endpoint that accepts…Source: Red Hat security advisory for CVE-2026-33671 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Cluster Observability Operator 1.5 | cluster-observability-operator/logging-console-plugin-pf4-rhel9:1782839279 | RHSA-2026:34342 |
| Red Hat Ceph Storage 9.2 | rhceph/rhceph-9-rhel10:1790843527 | RHSA-2026:86618 |
| 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-2026-33671 in your dependencies?
Find it across npm, including transitive dependencies.