9.2
CRITICAL CVSS 4.0
CVE-2026-42055
NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module vulnerability
Description

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. This vulnerability exists when the proxy_http_version to 2 or grpc_pass directives are used to proxy HTTP/2 traffic, the ignore_invalid_headers directive is set to off, and the large_client_header_buffers directive size is larger than 2 megabytes. A remote, unauthenticated attacker, along with conditions beyond their control, could send large headers while creating an upstream request. This may cause a heap-based buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

INFO

Published Date :

June 17, 2026, 2:04 p.m.

Last Modified :

June 17, 2026, 2:04 p.m.

Remotely Exploit :

Yes !

Source :

f5
Affected Products

The following products are affected by CVE-2026-42055 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 F5 nginx_plus
2 F5 nginx_open_source
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 HIGH 9dacffd4-cb11-413f-8451-fbbfd4ddc0ab
CVSS 4.0 CRITICAL 9dacffd4-cb11-413f-8451-fbbfd4ddc0ab
Solution
Update NGINX to a version that addresses the heap-based buffer overflow vulnerability.
  • Update NGINX to a fixed version.
  • Verify proxy and header configurations.
  • Disable ASLR if possible.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-42055 vulnerability anywhere in the article.

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.