security.txt

A small file at /.well-known/security.txt that tells security researchers how to report a vulnerability to you.

Defined in RFC 9116, it must contain a Contact field (an email or web form) and an Expires date, and can link to a policy and an encryption key. Without it, people who find a bug guess at an address or post it publicly. A short disclosure policy saying what you will do with a report makes good reports more likely.

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Related terms

CVE (Common Vulnerabilities and Exposures): A public catalog that gives each known security vulnerability one ID, such as CVE-2025-55182, so everyone talks about the same bug.
Zero-day: A vulnerability attackers know about or exploit before the vendor has a fix, so defenders have had zero days to patch.
OWASP Top 10: The OWASP Foundation’s list of the ten most critical web application security risks, updated every few years.

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