External risk intelligence

Remotion Arbitrary File Write Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-30121

A critical arbitrary file write vulnerability exists in a software library used for programmatic video creation. This flaw could permit unauthorized file modifications on affected systems if reachable. It is important to determine if this library is utilized and assess its integration into operations.

1Halo Surface Signal

External exposure likelihood

Halo Surface Signal score for CVE-2026-30121

Remotion is a software library used by developers to create videos programmatically. It is typically used in local development environments, build pipelines, or CI/CD workflows, rather than being deployed as a public-facing network service.

PCI scan relevance

PCI Relevance for CVE-2026-30121

Yes

CVE-2026-30121 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This critical vulnerability allows attackers to write files anywhere on the system. It is considered PCI relevant due to its high severity and potential impact on cardholder data.

Scan-prioritization guidance only—not a PCI DSS certification or ASV attestation.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in a software library used for programmatic video creation. This issue could potentially allow unauthorized modification of files on affected systems, posing a risk if the library is used in sensitive environments. The primary concern at this stage is to determine if our organization utilizes this specific library and, if so, to what extent it is integrated into our operations.

  • Software flaw allows unauthorized file writing.
  • Confirm if this library is in use.
  • Assess exposure and confirm relevance.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted input to the remotion application, which might allow them to write to arbitrary files on the system. This could lead to system compromise if sensitive files are overwritten or replaced with malicious content. The exact method of reaching the vulnerable component is not detailed in the provided information.

  • Requires network access to the application.
  • Triggered by specially crafted input.
  • Risk of arbitrary file overwrite.

Live Threat

Current exploitation, exposure, and threat context

When supported by the advisory, this vulnerability could allow an unauthenticated attacker to write arbitrary files to the system, potentially impacting service behavior and system integrity.

  • System files could be overwritten.
  • Unauthenticated network access could trigger it.
  • Service disruption and system compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

Given the description of remotion as a software library for programmatic video creation, likely used in development or build pipelines, ownership likely falls to application development teams or platform engineering responsible for the development environment. The initial practical step is to identify where remotion is used, confirm if those instances are exposed or critical, and then determine the accountable owner for remediation planning.

  • Application or platform engineering teams.
  • Verify remotion usage and exposure.
  • Plan remediation based on identified risk.

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

Free EASM Trial See How Signal Works

Frequently asked questions

What is remotion and how is it used?

Remotion is a software library that allows developers to create videos using programming languages like React. Instead of using traditional video editing tools, teams use it to automate the rendering of media, typically within their internal development workflows, build pipelines, or CI/CD environments where content is generated programmatically.

What does arbitrary file write mean for CVE-2026-30121?

This vulnerability is classified as CWE-123 (Write-What-Where condition). It means a flaw in the code allows an unauthorized user to write data to files on the host system that they should not have access to. In the context of this CVE, it could enable an attacker to overwrite critical system files or inject malicious content, potentially leading to full system compromise.

How is this vulnerability triggered?

An attacker triggers this flaw by sending specially crafted input to the remotion application. The system processes this input in a way that unintendedly executes a file write operation. Importantly, this does not happen through normal use of the software; it requires a malicious request specifically designed to exploit the underlying weakness in how the library handles file paths or data inputs.

Do I need to worry if my remotion instance is internal?

Halo Surface Signal indicates that remotion is typically used in isolated development or build environments rather than as a public-facing service. While internal usage is generally safer, you should still evaluate if your specific build server or development environment is reachable from untrusted networks, as the vulnerability requires network access to the application to succeed.

What is the first step to address this CVE?

Your initial priority is discovery. Work with your application development and platform engineering teams to identify every project or pipeline where the remotion library is integrated. Once you have a complete inventory, assess whether those specific environments are accessible via the network and prioritize remediation for any instances that are not properly secured.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished Modified