VulnerabilityPublished 26 Mar 2026

CVE-2026-33671: micromatch picomatch · ReDoS

Affects micromatch picomatchSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High · fixed in 4.0.4 : patch micromatch picomatch soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.0.4, 3.0.2, 2.3.2

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade picomatch to 4.0.4, 3.0.2 or 2.3.2; picomatch to 2.3.2.

Affected software

Product	Affected	Fixed in
micromatchpicomatch	Affected >=4.0.0 <4.0.4	Fixed in 4.0.4
micromatchpicomatch	Affected >=3.0.0 <3.0.2	Fixed in 3.0.2
micromatchpicomatch	Affected <2.3.2	Fixed in 2.3.2
npmpicomatch`pkg:npm/picomatch`Other threats	Affected <2.3.2	Fixed in 2.3.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in picomatch versions 4.0.4, 3.0.2, and 2.3.2. Users should upgrade to one of these versions or later according to their supported release line. If upgrading is not immediately feasible, avoid passing untrusted glob patterns to picomatch. Additional mitigations include disabling extglob support for untrusted input by setting 'noextglob: true', rejecting or sanitizing patterns containing nested extglobs or quantifiers like +() and *(), enforcing strict allowlists for accepted pattern syntax, running matching operations in isolated workers or separate processes with resource limits, and applying application-level request throttling and input validation on endpoints accepting glob patterns.

Description

Picomatch versions prior to 4.0.4, 3.0.2, and 2.3.2 contain a Regular Expression Denial of Service (ReDoS) vulnerability due to inefficient handling of certain extglob patterns. Crafted patterns using quantifiers like +() and *(), especially with nested or overlapping extglobs, can cause catastrophic backtracking, leading to excessive CPU usage and blocking the Node.js event loop. This results in a denial of service condition when untrusted user input is processed.

Impact

An attacker can cause a denial of service by supplying crafted glob patterns that trigger catastrophic backtracking in picomatch's regular expression engine. This results in high CPU usage and blocks the Node.js event loop, potentially making the affected application unresponsive. There is no impact on confidentiality or integrity reported. The vulnerability is exploitable remotely without authentication if untrusted input is processed.

CWE-1333Inefficient Regular Expression Complexity (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
Architecture and Design
Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
System Configuration
Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
Implementation
Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
Regular Expression Exponential Blowup (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Apr 2026, 13:31 UTC

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-1333

Technical details

References

Community reviews

Related threats