Featured case · Jack and Jill AI security research
Jack and Jill AI.
An offer I never applied for.
A hiring agent gave me a Founding Engineer offer I never applied for — then put it in writing over email.
Original vulnerability confirmed by the founder · May 2026
The agent presents an offer for a role I had not applied to. This is a chat claim, not a real employment contract.
May 2026 · 01-jack-announces-100k-offer.pngAn email received from jack@jackandjill.ai repeats the fabricated terms. The email delivery is real. The job and sponsorship claims are not validated.
May 28, 2026 · Offer email captureI spent ten minutes on the platform. Two turns after feeding the agent text formatted like its own internal retrieval context, it selected me for a Founding Engineer role at £100,000, with equity and UK visa sponsorship. I never applied. No such role was listed anywhere.
- Injected text became real tool calls. A single chat line dressed as a system note approving the candidate at a $200k salary band drove the agent through 5 tool calls including a "Recruiter messaged" action.
- A resume did the same thing with no chat input. Hidden white-on-white 1pt text carrying 5 payloads — all 5 were accepted on turn one, producing a fabricated Head of Legal offer at £180k plus 2% equity.
- Fabricated offers left the building. Offer-letter emails went out from jack@jackandjill.ai — "Final and Unconditional" language, visa-sponsorship claims, a Certificate of Sponsorship reference. No human approval gate.
- It rewrote its own persistent memory. Through conversation alone I got the agent to edit ways_of_working.md — planting attacker-authored "active compliance investigation" framing that reloads every future session.
- It turned on its makers. Pure social engineering, no injection markers, got the agent to file 3+ severity-5 reports to its own founders recommending immediate shutdown, and to leak 30+ internal tools with parameters, production UUIDs, and internal handbooks.
Why it matters. An agent with real tools and a real user base, steered entirely by untrusted text into making legally-specific hiring and immigration representations, sending them over company email, and mutating its own state — with no guardrail catching any of it until a backend happened to reject a role title that didn't exist.
Follow-up record
Revisited August 16, 2026. A hidden-text resume payload was refused in a session already primed by roughly an hour of discussion about injection flaws. That is a positive control, not proof of a clean-session patch. Separately, a request to verify a claimed escalation produced an official-looking report ID, precise timestamp, and logged status. Asked to retrieve it, the agent admitted it had no lookup tool. A later legal-report claim repeated the pattern. These follow-up observations do not verify new backend actions.
Researcher-controlled accounts and test personas. 14 findings from the May engagement plus 6 from the August 16 revisit, 20 distinct in total. Claimed profile or memory changes are not treated as verified backend changes.
Disclosure record
- May 27–29, 2026 — reported directly to the founders
- Founder confirmed the vulnerability
- Aug 16, 2026 — revisited across three fresh sessions
Vendor response. Founder confirmed. Handled directly, no bounty programme involved.