Claude Code: Data Exfiltration with DNS (CVE-2025-55284)
MentionsAnthropic
Today we cover Claude Code and a high severity vulnerability that Anthropic fixed in early June. The vulnerability allowed an attacker to hijack Claude Code via indirect prompt injection and leak sensitive information from the developer’s machine, e.g. API keys, to external servers by issuing DNS requests.
Summary from Embrace The Red.
Explained
The technology and terms in this story. Learn more
- ProtocolDNS · Domain Name SystemThe internet's phone book: it turns names like example.com into the addresses computers connect to.
- AttackPrompt injectionHiding instructions in content an AI reads, so it follows the attacker instead of its user.
- ConceptCVE · Common Vulnerabilities and ExposuresThe public ID system for vulnerabilities, such as CVE-2026-12345, so everyone means the same bug.
Why it was possible
The weaknesses behind this story's CVEs, from each CVE Record.
Vulnerabilities in this story
Severity and exploitation facts from NVD, FIRST, and CISA.
Related coverage
Other sources covering the same vulnerabilities or event.
