CVE-2026-33672
ADVISORY - githubSummary
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
Common Weakness Enumeration (CWE)
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Executable Regular Expression Error
GitHub
3.9
CVSS SCORE
5.3medium| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| picomatch | npm | - | - | >=4.0.0,<4.0.4 | 4.0.4 |
| picomatch | npm | - | - | <2.3.2 | 2.3.2 |
| picomatch | npm | - | - | >=3.0.0,<3.0.2 | 3.0.2 |
CVSS:3 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
The vulnerable system can be exploited without interaction from any user.
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.
There is no loss of confidentiality.
Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
There is no impact to availability within the impacted component.
NIST
3.9
CVSS SCORE
5.3mediumDebian
-
Red Hat
3.9
CVSS SCORE
5.3mediumChainguard
CGA-h3vp-4fv3-55pp
-