ChatGPT share link flaw could reach private chats, now fixed
Parameter showed that opening a crafted ChatGPT share link could run code in a signed-in session. OpenAI fixed it on 26 October, and no real-world attacks are reported.
On 28 October 2026, security firm Parameter published details of a ChatGPT flaw it reported to OpenAI on 18 October. A malicious conversation could be published as a normal share link. When a signed-in user opened it, the attacker's code ran inside that user's ChatGPT session.
The attack chained several features together, starting with a maths graph that loaded a keyboard library. That library accepted unverified messages from another frame, which allowed HTML to be injected and code to run on the chatgpt.com page.
In their proof of concept, using their own test accounts, the researchers listed recent conversations, retrieved a private one that had never been shared, and sent a small selected piece of it to an outside server. Parameter says the code could do anything the victim could do on the account.
OpenAI reproduced the report on 21 October and raised its severity from P2 to P1. Both web front ends were fixed by 26 October. Parameter does not report any attacks on real users, and MIXED News reports no exploitation in the wild. No user action is needed for this flaw.
Why it matters
A share link looks like a harmless document. Here, opening one was the only step required of the victim, and the page it opened sat on a domain people trust.
The bug also shows why a chat account deserves the same care as an email account. Chats often hold work drafts, personal questions and pasted secrets, and one signed-in session can reach all of them. A long chat history is a store of data, even if nobody planned it that way.
The fix was quick, and the research was reported privately. Even so, this is a reminder that deleting what you no longer need limits what any future flaw can reach.
What you can do
- Nothing is needed to get this fix, because OpenAI applied it on its side.
- Be a little more careful with share links from people you do not know, as you would with any unknown link.
- Delete old chats you no longer need, especially any that hold private details or keys.
- Review the links you have shared. On recent versions this sits under Settings, then Data controls, then Shared links. Menus can vary.
- Remember that anyone holding one of your share links can read that conversation and pass it on.
- Turn on multi-factor sign-in for your ChatGPT account.
Sources
Source: Parameter