XSS lets attackers run scripts in a victim's browser, enabling data theft or account abuse; contextual output encoding and CSP reduce risk.
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Background for this topic.
Cross-site scripting (XSS) is a web-application flaw in which attacker-controlled input is interpreted as script in another user’s browser. It can be stored in application data, reflected in an immediate response, or introduced by unsafe client-side code (DOM-based XSS). The script runs in the affected site’s origin, so it may read page content, alter requests, or perform actions available to the victim; impact depends on the victim’s privileges and the application’s defenses.
The primary mitigation is context-aware output encoding: treat untrusted data as text when inserting it into HTML, attributes, URLs, JavaScript, or CSS, and use safe DOM APIs such as textContent rather than unsafe HTML insertion. If user-authored HTML is required, apply a well-tested HTML sanitizer. A restrictive Content Security Policy can limit exploitability but is defense in depth, not a substitute for correct encoding. HttpOnly cookies can reduce direct cookie theft, but do not prevent XSS from performing in-session actions.
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PLUS: Firefox adds XSS protection; Leadership turnover at CISA; FTC exempts some data collection Infosec In Brief DNS vulnerabilities are being addressed 84 percent faster in the UK public sector thanks to an automated vulnerability scanning system established as part of a program kicked off early last year.…
DOM-XSS attacks have become scarce on Google websites since TT debuted Mozilla last week revised its position on a web security technology called Trusted Types, which it has decided to implement in its Firefox browser.…
With this zero-day, researchers say the 'scrappy' group is stepping up its operations The Winter Vivern cyber spy group is exploiting an XSS zero-day vulnerability in attacks on European governments.…
XSS marks the spot WordPress users with the Advanced Custom Fields plugin on their website should upgrade after the discovery of a vulnerability in the code that could open up sites and their visitors to cross-site scripting (XSS) attacks.…
School-friendly tool still not fully protected, privacy guru warns Screencastify, a popular Chrome extension for capturing and sharing videos from websites, was recently found to be vulnerable to a cross-site scripting (XSS) flaw that allowed arbitrary websites to dupe people into unknowingly activating their webcams.…