CVE-2022-50999 in Nokogiri
Summary
by MITRE • 08/25/2026
Nokogiri versions before 1.13.5 contain an integer overflow vulnerability in packaged libxml2 buffer handling functions that allows attackers to cause out-of-bounds memory writes. Attackers can exploit this by crafting multi-gigabyte XML files to trigger buffer overflows resulting in information disclosure, data modification, or denial of service.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/25/2026
The security flaw identified in Nokogiri versions prior to 1.13.5 stems from a critical integer overflow vulnerability embedded within the packaged libxml2 library's buffer handling mechanisms. This issue is fundamentally rooted in how memory allocation sizes are calculated and validated before being committed during XML parsing operations. When processing certain inputs, specifically those involving large or complex structures, the arithmetic used to determine buffer boundaries can wrap around due to exceeding maximum integer limits. This mathematical error results in a significantly smaller allocated buffer than what is actually required by the parser logic. Consequently, when data is written into this undersized memory region, it spills over into adjacent memory areas, creating an out-of-bounds write condition that compromises the integrity of the application's memory space.
From a technical perspective, this vulnerability aligns with CWE-190, which describes integer overflow or wraparound errors, and often leads to CWE-787, an out-of-bounds write. The exploitation vector relies on attackers crafting malicious XML documents that are multi-gigabytes in size or structured in ways that trigger the specific arithmetic conditions within libxml2's parsing engine. By carefully constructing these inputs, a remote attacker can force the application to perform memory writes beyond the intended buffer limits. This capability allows for arbitrary code execution if the overwritten memory contains function pointers or control data, as well as more subtle attacks such as information disclosure where sensitive data residing in adjacent heap regions is leaked to the attacker through error messages or subsequent read operations that access corrupted memory states.
The operational impact of this vulnerability is severe, affecting any application using Nokogiri for XML processing without proper input validation or resource limits. Denial of service is a primary concern, as the malformed parsing can cause crashes or instability in long-running services like web applications and API gateways. Furthermore, the potential for data modification poses significant risks to business logic integrity, while information disclosure could lead to the exposure of internal application secrets, user credentials, or other confidential data stored in memory adjacent to the parsed XML structures. Given that Nokogiri is widely used as a default XML parser in Ruby-based ecosystems, including popular frameworks like Rails and Sinatra, this vulnerability affects a broad surface area of internet-facing applications globally.
Mitigation strategies must prioritize immediate upgrading to Nokogiri version 1.13.5 or later, where the underlying libxml2 buffer handling has been patched to correctly validate integer calculations before memory allocation. Organizations should also implement defense-in-depth measures by configuring XML parsers with strict limits on document size and entity expansion depth to prevent resource exhaustion even if similar vulnerabilities exist in future updates. Input validation at the application layer is recommended as a secondary control, ensuring that only expected data formats are processed. Additionally, deploying runtime protection mechanisms such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) can mitigate the exploitability of memory corruption issues by making it harder for attackers to predict memory layouts or execute injected code. Monitoring logs for unusual spikes in XML parsing activity may also help detect attempted exploitation in real-time, aligning with ATT&CK techniques related to resource hijacking and potential command execution via binary wrapper vulnerabilities.