AIR researchers discovered a network-filtering vulnerability in Vercel Sandbox that could allow rogue AI agents to leak sensitive information despite outbound network allowlists. The technique uses a crafted digital certificate sent to an approved server to trigger a request from that server to an attacker-controlled destination. This creates an indirect exfiltration route without requiring the sandbox to contact the unauthorized destination itself, undermining the network restrictions intended to contain agents.
AIR notified Vercel, which reportedly said it needed time to determine how to patch the flaw; no available fix was reported in the October 13 coverage. Researchers described the vulnerability as apparently longstanding and found no evidence of exploitation in the wild, although they could not rule it out. Organizations running AI agents in Vercel Sandbox should review agents’ access to sensitive information and avoid treating network allowlists alone as a sufficient barrier against data exfiltration.

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According to AIR co-founder and CTO Niv Hoffman, Vercel said it needed time to develop a patch because the remediation approach was unclear. The report did not identify an available fix.
AIR contacted Vercel about the network-filtering vulnerability before the news report was published.
AIR researchers demonstrated that a crafted digital certificate sent to an approved server could cause that server to contact an attacker-controlled destination. The technique could indirectly exfiltrate sensitive information while the sandbox's own connections remain within its network allowlist.
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