Executive Summary

This vulnerability in uriparser through version 0.9.9 allows unbounded recursion and stack consumption when parsing large inputs containing many commas, specifically demonstrated by the function ParseMustBeSegmentNzNc.

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Impact Analysis

The vulnerability can lead to excessive stack consumption, potentially causing a denial of service due to stack overflow or application crash when processing specially crafted large inputs.

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Detection Guidance

This vulnerability can be detected by testing the uriparser library with specially crafted URI inputs containing many commas, such as a very long URI string composed of repeated '1,1,1,1,...' segments. A minimal example involves initializing a UriUriA structure and a UriParserStateA state, then attempting to parse the excessively long URI string to see if it triggers a stack overflow and causes the program to crash. Specific commands would depend on the environment but generally involve running a test program that uses uriparser to parse such inputs and monitoring for crashes or stack overflow errors. [2]

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Mitigation Strategies

Immediate mitigation steps include updating uriparser to version 0.9.9 or later, where the vulnerability has been fixed by refactoring recursive parsing functions into iterative ones to prevent stack overflow. Downstream projects, such as PHP, have also incorporated this patch, so updating dependent software to versions including this fix is recommended. Additionally, applying strong test coverage and fuzz testing against known-good URI parsers can help ensure the fix's effectiveness. [1]

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