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An NGINX vulnerability tracked as CVE-2026-42945 is being actively exploited by attackers. The flaw affects NGINX Open Source and NGINX Plus and could lead to server crashes or remote code execution under specific conditions.
Security researchers observed exploitation attempts within days of the vulnerability becoming public, highlighting how quickly attackers move to abuse flaws in widely used infrastructure software.
How the NGINX Vulnerability Works
The issue is caused by a heap buffer overflow in the NGINX worker process. Attackers can trigger the flaw by sending specially crafted HTTP requests to vulnerable servers.
Because the vulnerability does not require authentication, exposed systems are at higher risk. In many cases, attackers can crash the NGINX worker process, leading to service disruption. Under specific conditions, the flaw could also be leveraged for remote code execution.
Researchers noted that full remote code execution is more likely on systems where protections such as Address Space Layout Randomization (ASLR) are disabled.
The vulnerability mainly affects servers using specific rewrite configurations, meaning not every NGINX deployment is directly exploitable. However, identifying vulnerable systems at internet scale remains difficult.
Large Exposure and Security Recommendations
Security researchers estimate that millions of internet-facing NGINX servers could potentially be affected. Even if only a fraction of those systems meet the exact exploitation conditions, the overall attack surface remains significant.
Attackers are already scanning for vulnerable or misconfigured servers, increasing the urgency for organizations to respond quickly.
To reduce risk, security teams should:
- Apply the latest NGINX patches and updates
- Review rewrite configurations carefully
- Enable protections such as ASLR
- Monitor for suspicious or unusual HTTP requests
The incident highlights how vulnerabilities in widely deployed technologies can quickly become major security threats, even when exploitation depends on specific configurations.
With active exploitation already underway, rapid patching and continuous monitoring are critical to preventing compromise.
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