CVE-2026-76833 cgauge CVE debrief

Who should care

Node.js developers and administrators who use the @cgauge/yaml package in their applications should assess their exposure and take immediate action to mitigate the risk. This includes verifying the version of @cgauge/yaml in use, checking for patches or updates, and implementing compensating controls to validate and sanitize YAML input.

Why it matters

The CVE-2026-76833 vulnerability in the @cgauge/yaml npm package is significant because it allows for arbitrary code execution, potentially leading to full Node.js runtime authority compromise. Node.js applications parsing untrusted YAML input with this library are at risk.

• Potential full Node.js runtime authority compromise, allowing attackers to access environment variables, read and write files, access networks, and execute subprocesses.
• Exposure of sensitive data or functionality due to arbitrary JavaScript execution.
• Possible lateral movement within compromised systems or networks.
• Need for immediate verification of @cgauge/yaml version and implementation of compensating controls.

Technical summary

The @cgauge/yaml npm package contains an arbitrary code execution vulnerability that allows attackers to execute arbitrary JavaScript by embedding a custom !js YAML tag. The construct callback unconditionally calls eval() on attacker-supplied string values during document parsing, exposing full Node.js runtime authority. This vulnerability enables attackers to execute arbitrary JavaScript, potentially leading to full Node.js runtime authority compromise. Node.js applications parsing untrusted YAML input with this library are at risk, with potential impacts including environment variable access, filesystem read/write, network access, and subprocess execution. The vulnerability is significant because it allows an

Defensive priority

High

Recommended defensive actions

• Immediately assess if your Node.js applications use the @cgauge/yaml package and parse untrusted YAML input.
• Verify the version of @cgauge/yaml in use and check for any available patches or updates.
• Implement compensating controls, such as validating and sanitizing YAML input, to reduce the risk of exploitation.
• Monitor your applications for any suspicious activity that could indicate exploitation attempts.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability in the @cgauge/yaml npm package. The vulnerability allows for arbitrary code execution via a custom !js YAML tag, with potential impacts including full Node.js runtime authority compromise.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.