CVE-2021-28834
Description
A flaw was found in rubygem-kramdown. Rouge is a syntax highlighter used by kramdown. Restriction of the Rouge formatters to the Rouge::Formatters namespace does not occur when Ruby's const_get() method is called. This can lead to arbitrary classes being instantiated in situations where the application using kramdown, for example, accepts user input to select a Rogue syntax highlighter formatter. The highest threat from this vulnerability when exploited in a vulnerable configuration is to data confidentiality, integrity, and availability.
Statement
Red Hat supported products are not affected by this flaw because they do not ship rubygem-kramdown.
Mitigation
Developers using rubygem-kramdown: Do not pass user or external input into custom Rouge formatter selection logic.
All other users/system administrators: There is no known mitigation at this time.
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability,Other
Technical Impact: Execute Unauthorized Code or Commands; Alter Execution Logic
The attacker might be able to execute code that is not directly accessible to the attacker. Alternately, the attacker could call unexpected code in the wrong place or the wrong time, possibly modifying critical system state.
Availability,Other
Technical Impact: DoS: Crash, Exit, or Restart; Other
The attacker might be able to use reflection to call the wrong code, possibly with unexpected arguments that violate the API (CWE-227). This could cause the product to exit or hang.
Confidentiality
Technical Impact: Read Application Data
By causing the wrong code to be invoked, the attacker might be able to trigger a runtime error that leaks sensitive information in the error message, such as CWE-536.
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