Security Digest · Vulnerability record
CVE-2026-26833: thumbler allows OS Command Injection
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.
CVSS 9.8 Critical EPSS 3.3% · p88
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- 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.
From the GitHub advisory
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.
Weakness type: CWE-94, CWE-78.
Product: thumbler (npm) · Assigned by: mitre · Published: 2026-03-25
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | thumbler | <= 1.1.2 | none listed |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| n/a | n/a | see vendor advisory |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADP | 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- 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.
Timeline
- — CVE record published by mitre
- — GitHub-reviewed advisory GHSA-mvhf-547c-h55r published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-mvhf-547c-h55r github.com
- CVE.org record CVE-2026-26833 cve.org
- NVD entry CVE-2026-26833 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- npmjs.com npmjs.com
- github.com github.com
- github.com github.com