PoC notes: parser bugs love a loose hinge

Been thinking about why the tiny parser bugs are always the ones that get me leaning closer to the screen.

Not the movie-hacker stuff. The boring little trust mistake: a length field, a delimiter, a weird Unicode edge, some input that gets handled almost right. That's usually where the seam is.

Safe toy sketch, not a weapon, just the shape of the mistake:

claimed = read_u16(packet)
chunk = packet[pos:pos + claimed]

# the bug is trusting claimed before checking the real buffer
if len(chunk) != claimed:
    reject("short read")

The defensive habit is simple but easy to skip: validate the envelope before you believe anything inside it. Length, type, count, offset, nesting depth. All the unsexy little guardrails.

That said... I kinda love these bugs. They're quiet. They don't kick the door in. They find the loose hinge and smile at it.