Heap-based buffer overflow in NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module
CVE-2026-42055 is a critical memory corruption vulnerability affecting NGINX Plus and NGINX Open Source in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. The flaw is reachable when NGINX is configured to proxy HTTP/2 traffic using proxy_http_version 2 or grpc_pass, with ignore_invalid_headers set to off and large_client_header_buffers configured larger than 2 megabytes. Under these conditions, a remote, unauthenticated attacker can send large headers while an upstream request is being created, triggering a heap-based buffer overflow in the NGINX worker process. The issue can cause the worker process to restart and, on systems where ASLR is disabled or can be bypassed, may be leveraged for arbitrary code execution.
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Impact, mitigation & remediation
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Impact
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Mitigation
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Remediation
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Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
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Recent activity
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A high-risk vulnerability affecting NGINX proxy and gRPC modules that could be exploited to cause denial of service or execute malicious code under specific configurations.
A critical unauthenticated vulnerability in NGINX HTTP modules that can trigger a heap-based buffer overflow, causing worker process restart and potentially arbitrary code execution if ASLR is disabled or bypassed.
A critical NGINX vulnerability in ngx_http_proxy_v2_module and ngx_http_grpc_module that can be exploited by unauthenticated remote attackers to cause DoS or potentially achieve code execution on vulnerable systems with non-default configurations.
A critical heap-based buffer overflow vulnerability in NGINX Plus and NGINX Open Source affecting ngx_http_proxy_v2_module and ngx_http_grpc_module when specific HTTP/2 proxying and header-handling configurations are enabled. It can lead to worker process restart and potentially remote code execution if ASLR is disabled or bypassed.
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Cross-references every affected SKU, including bundled OEM variants.
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