x.com/tenobrus/status/2039009487865135224

This sentence collapses two distinct concepts into one.

Authoritative security sources define a software vulnerability as a security weakness that can be exploited by an attacker. NIST's glossary defines a software vulnerability as "a security flaw, glitch, or weakness found in software code that could be exploited by an attacker," and Microsoft says a security vulnerability is "a weakness in the computational logic" that, when exploited, harms confidentiality, integrity, or availability.

By contrast, NIST explicitly describes bug, weakness, and vulnerability as separate notions with causal relations between them, not as identical categories. Its 2023 publication Bug, Fault, Error, or Weakness: Demystifying Software Security Vulnerabilities says it "define[s] the notions of software bug, weakness, and vulnerability ... and elucidate[s] their causal relations."

OWASP also distinguishes vulnerabilities from generic bugs by defining a vulnerability as a weakness in an application "which can be a design flaw or an implementation bug" that allows an attacker to cause harm. That directly contradicts the post's claim in both directions:

• Not every bug is a vulnerability: many bugs are reliability, usability, or correctness defects with no exploitable security impact.
• Not every vulnerability is simply a bug: vulnerabilities can arise from broader design flaws and security weaknesses, not just ordinary coding mistakes.

So there is a meaningful separation in standard security practice, even though the categories can be related and sometimes overlap.