Claude Code Sends Email Addresses to Websites
agents claude
| Source: HN | Original article
Claude Code inadvertently includes users' email addresses in the User-Agent headers it sends to websites, exposing personal data to visited sites.
Claude Code’s privacy flaw has been patched, but the saga reveals a broader leak than first reported. Anthropic confirmed that, until the rollout of version 2.1.317 in early 2024, the assistant not only inserted users’ registered email addresses into the User‑Agent header of every web request, it also embedded the same address in the system‑prompt that seeds each session. The dual exposure, which had been present since at least July 2023, meant that any server logging the header and any downstream model receiving the prompt could harvest a “scam‑ready” lead. The built‑in fix in 2.1.317 automatically strips the email from both the header and the prompt, eliminating the need for the manual five‑minute workaround that earlier guides described.
The leak first entered the public eye through a plain‑English tutorial on explainx.ai, which showed how the User‑Agent header could carry the account email and offered a step‑by‑step fix. The guide noted that the issue affected anyone using Claude Code in a web‑enabled context, such as when the assistant fetched external documentation or interacted with online services. Shortly after, a Hacker News discussion argued the exposure was likely an isolated coincidence rather than a deliberately built‑in feature, while a separate commentary described a scenario where the assistant allegedly transmitted a user’s email to a restaurant’s kitchen system, underscoring real‑world risks.
The privacy debate intensified as the User‑Agent header is routinely logged by web servers, allowing third parties to collect personal identifiers without consent. Adding the system‑prompt leak widened the attack surface: any downstream AI component that receives the prompt now also sees the email. The timing coincides with Claude’s expansion into consumer‑facing tools, most recently a Personal Finance feature that analyses spending, raising questions about Anthropic’s balance between functionality and data protection.
Anthropic has not yet detailed the internal timeline that led to the July 2023 discovery, but the rapid deployment of the 2.1.317 mod after the issue went viral suggests a swift response to community pressure. Observers will watch for further transparency measures, such as default‑off metadata transmission and clearer documentation. The episode adds pressure on AI providers across the Nordics to adopt privacy‑by‑design practices, a theme likely to shape upcoming regulatory scrutiny in the region.
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