---
title: "CVE-2026-26833: thumbler allows OS Command Injection"
url: https://erroneo.us/security/cve/CVE-2026-26833/
description: "CVE-2026-26833 (thumbler (npm)): thumbler through 1.1.2 allows OS command injection via the input, output, time, or size parameter in the thumbnail()…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-03-25
date_modified: 2026-03-31
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-26833"
kev: false
cvss: 9.8
epss: 0.03305
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-26833: thumbler allows OS Command Injection

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 3.3% , percentile 88: FIRST’s model estimates a 3.3% chance of exploitation activity in the next 30 days, higher than 88% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes thumbler (npm) <= 1.1.2, no fixed version listed . Check your lockfile, including transitive dependencies.

## What it is

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 childprocess.exec() without proper sanitization or escaping.

## Affected packages

- npm `thumbler` <= 1.1.2 → fixed: none listed

## Affected products (CVE record)

- n/a n/a: see advisory

## Severity

- CISA-ADP CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 3.31% probability of exploitation activity in the next 30 days; percentile 88.

## Sources

- [GitHub Advisory GHSA-mvhf-547c-h55r](https://github.com/advisories/GHSA-mvhf-547c-h55r)
- [CVE.org record CVE-2026-26833](https://www.cve.org/CVERecord?id=CVE-2026-26833)
- [NVD entry CVE-2026-26833](https://nvd.nist.gov/vuln/detail/CVE-2026-26833)
- [github.com](https://github.com/mmahrous/thumbler)
- [npmjs.com](https://www.npmjs.com/package/thumbler)
- [github.com](https://github.com/mmahrous/thumbler/blob/master/lib/thumbler.js)
- [github.com](https://github.com/zebbernCVE/CVE-2026-26833)

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Source page: https://erroneo.us/security/cve/CVE-2026-26833/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt