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I work on security at PostHog. We resolved these SSRF findings back in October 2024 when this report was responsibly disclosed to us. I'm currently gathering the relevant PRs so that we can share them here. We're also working on some architectural improvements around egress, namely using smokescreen, to better protect against this class of issue.

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Here's the PR[0] that resolved the SSRF issue. This fix was shipped within 24 hours of receiving the initial report.

It's worth noting that at the time of this report, this only affected PostHog's single tenant hobby deployment (i.e. our self hosted version). Our Cloud deployment used our Rust service for sending webhooks, which has had SSRF protection since May 2024[1].

Since this report we've evolved our Cloud architecture significantly, and we have similar IP-based filtering throughout our backend services.

[0] https://github.com/PostHog/posthog/pull/25398

[1] https://github.com/PostHog/posthog/commit/281af615b4874da1b8...

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