CVE-2025-6494 in nokogiri
Summary
by MITRE • 06/23/2025
A vulnerability was found in sparklemotion nokogiri up to 1.18.7. It has been classified as problematic. This affects the function hashmap_get_with_hash of the file gumbo-parser/src/hashmap.c. The manipulation leads to heap-based buffer overflow. An attack has to be approached locally. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 06/30/2025
The vulnerability identified as CVE-2025-6494 represents a critical heap-based buffer overflow in the nokogiri library version 1.18.7 and earlier, specifically within the hashmap_get_with_hash function located in gumbo-parser/src/hashmap.c. This flaw resides in the foundational parsing components that handle HTML and XML document processing, making it particularly dangerous for applications that process untrusted input through the nokogiri gem. The issue stems from improper bounds checking during hash table operations, where an attacker can manipulate input data to cause memory corruption that extends beyond the allocated buffer boundaries. This vulnerability type falls under CWE-121 heap-based buffer overflow, which is classified as a serious memory safety issue that can lead to arbitrary code execution or system compromise.
The technical exploitation of this vulnerability requires local access and involves manipulating the hashmap data structure to trigger the buffer overflow condition. When the hashmap_get_with_hash function processes specific input patterns, it fails to validate the size of data being read or written, allowing an attacker with local privileges to craft malicious input that overflows the heap allocated buffer. The attack vector specifically targets the internal memory management of the HTML parser component, where the function attempts to retrieve values from a hash table without adequate bounds verification. This type of vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1555.003 for credentials from password storage components, as successful exploitation could provide attackers with elevated privileges or access to sensitive data stored in memory.
The operational impact of CVE-2025-6494 extends beyond immediate system compromise to encompass potential denial of service scenarios and data integrity violations across applications relying on nokogiri for document processing. Given that nokogiri is a widely used ruby gem for parsing HTML and XML content, applications in production environments that handle user-submitted content, web scraping operations, or document conversion services become particularly vulnerable. The public disclosure of exploitation techniques means that threat actors can readily develop automated tools to target affected systems, increasing the risk profile significantly. Organizations using nokogiri versions prior to 1.18.8 should immediately assess their attack surface and implement mitigation strategies, as the vulnerability can potentially be leveraged to execute arbitrary code with the privileges of the affected application process.
Mitigation strategies for this vulnerability should prioritize immediate version upgrades to nokogiri 1.18.8 or later, which contain patches addressing the buffer overflow condition in the hashmap implementation. System administrators should also implement runtime protections such as address space layout randomization and stack canaries to reduce exploit reliability, while monitoring for suspicious memory access patterns that may indicate exploitation attempts. The remediation process should include comprehensive code review of any applications that utilize nokogiri, particularly those handling untrusted input, to identify potential additional attack vectors that could leverage similar memory safety issues. Additionally, organizations should establish vulnerability management processes that include regular security scanning and dependency updates to prevent similar issues from arising in other components of their software supply chain, as this vulnerability demonstrates the critical importance of maintaining up-to-date parsing libraries in security-sensitive applications.