CVE-2026-26833: Thumbler Thumbler Allows OS Command Injection Vulnerability

CRITICAL
Advisory Identifier: GHSA-mvhf-547c-h55r
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CVSS 9.8
CWE-78 CWE-94
Published
Advisory Summary

CVE-2026-26833 is a CRITICAL (CVSS 9.8) thumbler allows os command injection vulnerability (CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')) affecting Thumbler libraries in the npm ecosystem. The issue involves thumbler allows os command injection. Remediation is available in the latest vendor maintenance releases.

CVE-2026-26833 at a Glance

CVE Identifier CVE-2026-26833
GHSA Identifier GHSA-mvhf-547c-h55r
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Affected Product Thumbler
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-26833

To remediate this vulnerability, upgrade all affected Thumbler dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

thumbler fixed: Latest secure release 
npm install thumbler@Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls thumbler

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-26833, inspect your project dependencies using npm:

npm ls thumbler

Analyze the terminal output to locate any version of Thumbler in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The npm ls thumbler command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'), where the product constructs all or part of an os command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended os command when it is sent to a downstream component. In Thumbler, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

thumbler through 1.1.2 allows OS command injection via the input, output, time, or size parameter in the thumbnail() function because user input is concatenated into a shell command string passed to child_process.exec() without proper sanitization or escaping.

CVE-2026-26833 Affected Thumbler Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
thumbler
npm/thumbler
npm
≤ 1.1.2

References

NVD — CVE-2026-26833 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-26833
Thumbler Source Repository REPOSITORY
https://github.com/mmahrous/thumbler
Thumbler Source Repository REPOSITORY
https://github.com/mmahrous/thumbler/blob/master/lib/thumbler.js
Thumbler Source Repository REPOSITORY
https://github.com/zebbernCVE/CVE-2026-26833
www.npmjs.com/package/thumbler WEB
https://www.npmjs.com/package/thumbler

Frequently Asked Questions

What is CVE-2026-26833?
CVE-2026-26833 is a security vulnerability in Thumbler involving thumbler allows OS Command Injection under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection').
Which Thumbler versions are affected?
Affected versions include releases prior to current release patches across affected packages: thumbler.
What version fixes CVE-2026-26833?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is thumbler affected?
Yes, thumbler is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-26833?
CVE-2026-26833 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-26833?
CVE-2026-26833 is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') (The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.).
How can I check npm dependencies for CVE-2026-26833?
Run the dependency tree command: 'npm ls thumbler'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-mvhf-547c-h55r",
  "modified" : "2026-03-31T23:24:12Z",
  "published" : "2026-03-25T18:31:47Z",
  "aliases" : [ "CVE-2026-26833" ],
  "summary" : "thumbler allows OS Command Injection",
  "details" : "thumbler through 1.1.2 allows OS command injection via the input, output, time, or size parameter in the thumbnail() function because user input is concatenated into a shell command string passed to child_process.exec() without proper sanitization or escaping.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "thumbler"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.1.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-26833"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mmahrous/thumbler"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mmahrous/thumbler/blob/master/lib/thumbler.js"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/zebbernCVE/CVE-2026-26833"
  }, {
    "type" : "WEB",
    "url" : "https://www.npmjs.com/package/thumbler"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78", "CWE-94" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-31T23:24:12Z",
    "nvd_published_at" : "2026-03-25T16:16:21Z"
  }
}