Skip to content
OpenAdvisories

Vendor

w3c

4 known vulnerabilities.

Products

CSS Validator 1 Unicorn 1 online-spellchecker-py 1 websub 1
All Critical High Medium Low Exploited only Public exploit

1 result · Clear filters · Feed

  • Medium 5.7
    CVE-2026-50571

    WebSub: Reflected script execution through intent-verification challenges

    WebSub is a W3C recommendation produced by the Social Web Working Group. In recommendation REC-websub-20180123, the intent-verification protocol requires a subscriber to echo the `hub.challenge` value, also exposed as `hub_challenge` by some frameworks, but d…

    w3c websub