I think it was this one [1]. The story is older than I remember (2015) but at the time I was working on aircraft system design and knew people well-versed in ARINC 664 and everything related to aircraft data network segregation between domains.
And a lot of the noise was coming from Boeing requesting Special Conditions [2] for the certification of recent airliners where segregation is less absolute than when systems had a floppy reader to install updates.
> Hacker Chris Roberts claimed he was able to break into the in-flight entertainment system up to 20 times on separate flights and that on one flight he was able to make the plane “climb” and “move sideways” by accessing flight control systems from a laptop in his seat.
[1] https://www.theguardian.com/technology/2015/may/19/hacker-ch...
[2] https://www.federalregister.gov/documents/2007/12/28/E7-2507...