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

> An attacker can execute arbitrary OS commands by injecting malicious input into the thumbnail function parameters in the thumbler library.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Mar 2026
- **Updated:** 28 Mar 2026
- **Also known as:** GHSA-mvhf-547c-h55r

## What is CVE-2026-26833?

CVE-2026-26833 is a critical command injection vulnerability in n/a, published on 25 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2026-26833?

2 open source packages ship an affected version, including thumbler. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `thumbler` | npm | All versions to 1.1.2 | None |
| `thumbler` | npm | All versions to 1.1.2 | None |

Products: Mmahrous Thumbler.

## How do I fix CVE-2026-26833?

No fix has been published for CVE-2026-26833 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-26833 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-26833 exists.

Public exploit code:

- Advisory for thumbler (github_poc): https://github.com/zebbernCVE/CVE-2026-26833

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-26833 and fix it if it is affected.

What it is: CVE-2026-26833 is a critical command injection vulnerability in n/a, published on 25 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-26833 exists.

Affected packages and fixed versions:
- thumbler (npm): affected all versions up to 1.1.2; no fix listed
- thumbler (npm): affected all versions up to 1.1.2; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-26833/ (Markdown: https://insights.sbomify.com/CVE-2026-26833/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-26833
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-26833
- OSV: https://osv.dev/vulnerability/CVE-2026-26833

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-26833/
Summaries are generated and may contain mistakes; the official description above is the record.