CVE-2025-6490 in nokogiri
Summary
by MITRE • 06/23/2025
A vulnerability was found in sparklemotion nokogiri up to 1.18.7 and classified as problematic. This issue affects the function hashmap_set_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 • 05/28/2026
The vulnerability identified as CVE-2025-6490 represents a critical heap-based buffer overflow within the nokogiri library version 1.18.7 and earlier, specifically within the hashmap_set_with_hash function located in gumbo-parser/src/hashmap.c. This flaw exists in the parsing component of the library that processes html and xml documents, making it a significant concern for applications that rely on nokogiri for document processing. The vulnerability is classified as problematic due to its potential to cause system instability and unauthorized code execution when exploited.
The technical nature of this vulnerability stems from improper bounds checking within the hashmap_set_with_hash function, which handles hash table operations during document parsing. When processing malformed or specially crafted input data, the function fails to validate the size of data being written to heap memory, creating a condition where an attacker can overflow adjacent memory regions. This heap-based buffer overflow occurs because the implementation does not properly validate input parameters or enforce memory allocation limits before writing data to allocated buffers. The vulnerability specifically manifests when the parser encounters certain input patterns that trigger the problematic code path within the hash table implementation.
The operational impact of CVE-2025-6490 is substantial as it allows for local privilege escalation and potential system compromise when exploited. Since the attack requires local access to the system, it can be particularly dangerous in environments where applications running with elevated privileges process untrusted input through nokogiri. The heap overflow can lead to memory corruption that may result in denial of service conditions, arbitrary code execution, or data leakage. Applications using nokogiri for parsing user-provided content, web scraping, or document processing are particularly at risk, especially when these applications run with higher privileges or process sensitive data. The public disclosure of this exploit increases the likelihood of real-world attacks against vulnerable systems.
Mitigation strategies for CVE-2025-6490 should prioritize immediate patching of affected nokogiri versions to 1.18.8 or later, which contains the necessary fixes for the hashmap buffer overflow issue. System administrators should implement input validation and sanitization measures to reduce the attack surface, particularly when processing untrusted content through nokogiri. The vulnerability aligns with CWE-121 heap-based buffer overflow classification and may be leveraged through techniques described in ATT&CK matrix under T1059 command and scripting interpreter and T1068 local privilege escalation. Organizations should also consider implementing application sandboxing, memory protection mechanisms, and monitoring for suspicious memory access patterns to detect potential exploitation attempts. Additionally, regular security assessments and dependency updates should be enforced as part of the overall security posture to prevent similar vulnerabilities from being introduced through third-party libraries.