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How CVE-2026-44479 Works
This vulnerability arises when the Vercel CLI operates in non-interactive mode (often used in CI/CD pipelines or with AI agents). It occurs in a chain of three conditions:
1. `–token` in Command Arguments: The user authenticates by passing a token directly on the command line using the `–token` (or -t) flag. Using the `VERCEL_TOKEN` environment variable is not affected.
2. Non-Interactive Mode Active: The CLI is forced into a non-interactive state, either by the explicit `–non-interactive` flag or by being auto-detected as running within an AI agent environment.
3. Command Failure in Non-Interactive Mode: The executed command cannot be completed on its own without user input, for example, because the `–yes` flag is missing to approve a destructive action, or because there is an ambiguous scope that would normally require a selection.
When all three conditions are true, the Vercel CLI’s error-handling mechanism generates a structured JSON payload. This payload is meant to provide actionable assistance to the AI agent or CI system. However, the CLI inadvertently includes the full command line used to invoke it, which still contains the plaintext `–token` value, verbatim within this JSON output. This leaked token can then be captured in CI/CD build logs, agent transcripts, or any system that logs the CLI’s standard output or error streams.
DailyCVE Form
Platform: Vercel CLI
Version: All vulnerable versions
Vulnerability : Information Disclosure
Severity: Medium
date: 2026-04-30
Prediction: Patch available 2026-04-30
What Undercode Say:
To prevent this issue, never pass tokens as command-line arguments. The following demonstrates the insecure and secure methods of authentication with the Vercel CLI:
❌ BAD: Token leaks in shell history, process listings, and automation logs vercel deploy --token "vca_abc123" ✅ GOOD: CLI reads VERCEL_TOKEN securely from the environment export VERCEL_TOKEN="vca_abc123" vercel deploy
For verifiable token usage in automation scripts, always ensure the environment variable is loaded before CLI execution.
How Exploit:
An attacker with read access to the execution logs of a compromised CI/CD tool, an AI agent transcript, or a build system could grep for the specific `vca_` prefix used by Vercel tokens to steal the exposed credential, leading to unauthorized project deployments and data access.
Protection from this CVE
- Upgrade Vercel CLI: Ensure you are running the latest patched version of the Vercel CLI.
- Rotate Exposed Tokens: If your automation ever used the `–token` flag in the past, assume the token has been compromised and revoke it immediately.
- Always Use Environment Variables: Prefer authenticating via the `VERCEL_TOKEN` environment variable instead of the `–token` flag.
- Sanitize Logs: Regularly scan and sanitize CI/CD and system logs to ensure residual secrets are not stored inadvertently.
Impact
- Direct Impact: The plaintext Vercel API token is written to automation logs, where it can be intercepted by anyone with access to the logs.
- Indirect Impact: An attacker using a leaked token could impersonate the token owner to deploy malicious code, access environment variables or project settings, and potentially pivot to other connected cloud services.
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Sources:
Reported By: github.com
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