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Holy shit. My relatives have asked me in the past "could this [image|video|other supposedly innocuous file format] be a virus or hack my phone?". I've always told them not to worry. Can't do that anymore.
https://en.wikipedia.org/wiki/Windows_Metafile_vulnerability Long story short: Windows library routines for handling an obscure, obsolete image format had a parser flaw. Simply rendering an appropriately crafted image via the standard Windows APIs -- whether in a web browser, file explorer, file preview, word processor, anywhere -- resulted in kernel-level arbitrary code execution. Now, we've gotten a bit smarter abo…
Bit of a caveat: Chromium and Firefox are probably some of the most hardened software programs in the world (for other browsers, all bets are off).
Chromium distributes its logic over multiple processes per tab, so that even if you eg find a zero-day in V8, you still can't use it to get arbitrary file access without a sandbox escape. Last I checked, Firefox was getting there. Also, Firefox compiles some parsing and image processing libraries to WebAssembly for another layer of sandboxing (and to protect against ROP exploits), and increasingly uses Rust for sensitive tasks.
That's not to say they're safe, but I don't think they're the biggest source of exploits.