CVE-2026-26833
Published: 25 March 2026
Summary
CVE-2026-26833 is a critical-severity OS Command Injection (CWE-78) vulnerability in Mmahrous Thumbler. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 18.9% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-10 (Information Input Validation).
Deeper analysis
CVE-2026-26833 is an OS command injection vulnerability affecting the thumbler npm package through version 1.1.2. The flaw occurs in the thumbnail() function within lib/thumbler.js, where user-supplied values for the input, output, time, or size parameters are concatenated directly into a shell command string passed to child_process.exec() without sanitization or escaping. This issue corresponds to CWE-78 (Improper Neutralization of Special Elements used in an OS Command) and CWE-94 (Improper Control of Generation of Code), earning a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
A remote, unauthenticated attacker can exploit this vulnerability over the network with low complexity and no user interaction required. By supplying malicious payloads in the affected parameters, the attacker can inject arbitrary OS commands, leading to remote code execution on the host system. Exploitation could result in high-impact compromise, including unauthorized data access, modification, or disruption of the affected application.
Mitigation details and patches can be found in the referenced advisories, including the thumbler GitHub repository (https://github.com/mmahrous/thumbler), source code (https://github.com/mmahrous/thumbler/blob/master/lib/thumbler.js), dedicated CVE repository (https://github.com/zebbernCVE/CVE-2026-26833), and npm package page (https://www.npmjs.com/package/thumbler). The vulnerability was published on 2026-03-25.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-15463
Vulnerability 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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE enables remote unauthenticated OS command injection via unsanitized parameters in child_process.exec(), facilitating exploitation of public-facing applications (T1190) and Unix Shell command execution (T1059.004).
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Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SI-10 directly prevents OS command injection by requiring validation and sanitization of user-supplied input, output, time, and size parameters before concatenation into shell commands executed by child_process.exec().
SI-2 mandates timely identification, reporting, and correction of flaws like this command injection vulnerability in the thumbler package through patching to version beyond 1.1.2.
RA-5 requires vulnerability scanning of software dependencies like the thumbler npm package to detect CVE-2026-26833 and trigger remediation.