CVE-2025-58190 identifies a denial of service vulnerability in the golang.org/x/net/html package, specifically within the html.Parse function. The root cause is a loop with an unreachable exit condition (CWE-835), which causes the parser to enter an infinite loop when processing certain malformed or specially crafted HTML inputs. This infinite loop leads to resource exhaustion, primarily CPU, resulting in a denial of service condition. The vulnerability affects all versions of the package prior to a patch, with no version explicitly fixed at the time of publication. The flaw is particularly critical in environments where untrusted HTML content is parsed, such as web servers, proxies, or content management systems written in Go. While no exploits have been observed in the wild, the vulnerability is straightforward to trigger by supplying malicious HTML content to the parser. The absence of a CVSS score suggests the need for an internal severity assessment. The vulnerability impacts availability but does not directly compromise confidentiality or integrity. The attack vector is remote and unauthenticated, requiring only that the attacker can supply crafted HTML to the vulnerable parser. This makes it a significant risk for denial of service attacks against Go-based services that parse HTML input from untrusted sources.

For European organizations, the primary impact of CVE-2025-58190 is the risk of denial of service attacks against services and applications that utilize the golang.org/x/net/html package for HTML parsing. This can lead to service outages, degraded performance, and potential disruption of business-critical web applications, especially those handling user-generated or external HTML content. Industries such as finance, e-commerce, government, and telecommunications that rely on Go-based infrastructure could face operational interruptions. The vulnerability could be exploited to target public-facing web services, causing downtime and impacting availability commitments under regulations like GDPR, which emphasize service reliability and data protection. Additionally, denial of service conditions may indirectly affect incident response and security monitoring capabilities. Since the vulnerability does not require authentication, any exposed service parsing HTML is at risk, increasing the attack surface. The impact is thus significant for organizations with high availability requirements and those operating critical infrastructure in Europe.

Organizations should monitor golang.org/x/net/html package updates and apply patches promptly once available to address CVE-2025-58190. Until a patch is released, implement strict input validation to filter or sanitize HTML content before parsing, reducing the likelihood of triggering the infinite loop. Employ resource usage limits and timeouts around HTML parsing operations to prevent CPU exhaustion from malicious inputs. Consider isolating parsing functions in sandboxed environments or separate processes to contain potential denial of service effects. Review and update incident response plans to detect and mitigate DoS attacks targeting HTML parsing components. For internally developed applications, audit code to identify usage of the vulnerable package and refactor if necessary. Additionally, network-level protections such as rate limiting and web application firewalls (WAFs) can help mitigate attack attempts by limiting the volume of malicious HTML requests. Finally, educate developers and security teams about this vulnerability to ensure awareness and proactive defense.