Spring Framework, version 5.1, versions 5.0.x prior to 5.0.10, versions 4.3.x prior to 4.3.20, and older unsupported versions on the 4.2.x branch provide support for range requests when serving static resources through the ResourceHttpRequestHandler, or starting in 5.0 when an annotated controller returns an org.springframework.core.io.Resource. A malicious user (or attacker) can add a range header with a high number of ranges, or with wide ranges that overlap, or both, for a denial of service attack. This vulnerability affects applications that depend on either spring-webmvc or spring-webflux. Such applications must also have a registration for serving static resources (e.g. JS, CSS, images, and others), or have an annotated controller that returns an org.springframework.core.io.Resource. Spring Boot applications that depend on spring-boot-starter-web or spring-boot-starter-webflux are ready to serve static resources out of the box and are therefore vulnerable.

A path traversal exists in markdown-pdf version <9.0.0 that allows a user to insert a malicious html code that can result in reading the local files.

Spring Framework, versions 5.0.x prior to 5.0.7 and 4.3.x prior to 4.3.18 and older unsupported versions, allows web applications to enable cross-domain requests via JSONP (JSON with Padding) through AbstractJsonpResponseBodyAdvice for REST controllers and MappingJackson2JsonView for browser requests. Both are not enabled by default in Spring Framework nor Spring Boot, however, when MappingJackson2JsonView is configured in an application, JSONP support is automatically ready to use through the "jsonp" and "callback" JSONP parameters, enabling cross-domain requests.

Spring Framework (versions 5.0.x prior to 5.0.7, versions 4.3.x prior to 4.3.18, and older unsupported versions) allow web applications to change the HTTP request method to any HTTP method (including TRACE) using the HiddenHttpMethodFilter in Spring MVC. If an application has a pre-existing XSS vulnerability, a malicious user (or attacker) can use this filter to escalate to an XST (Cross Site Tracing) attack.

An issue was discovered in markdown2 (aka python-markdown2) through 2.3.5. The safe_mode feature, which is supposed to sanitize user input against XSS, is flawed and does not escape the input properly. With a crafted payload, XSS can be triggered, as demonstrated by omitting the final '>' character from an IMG tag.

Cross-site scripting (XSS) vulnerability in the Markdown Preview Plus extension before 0.5.7 for Chrome allows remote attackers to inject arbitrary web script or HTML into some web applications via the upload and display of crafted text, markdown, or rst files that are designed to be viewed in the browser as plain text, but that will be converted to HTML without proper sanitization.

markdown-it before 4.1.0 does not block data: URLs.

The Markdown on Save Improved plugin 2.5 for WordPress has a stored XSS vulnerability in the content of a post.

Cross-site scripting (XSS) vulnerability in the Markdown on Save Improved plugin before 2.5.1 for WordPress allows remote attackers to inject arbitrary web script or HTML via unspecified vectors.

Cross-site scripting (XSS) vulnerability in the live preview feature in the Markdown Preview module 6.x for Drupal allows remote attackers to inject arbitrary web script or HTML via "Markdown input."