Heap-based Buffer Overflow in NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module
CVE-2026-42055 is a heap-based buffer overflow in NGINX Plus and NGINX Open Source affecting the ngx_http_proxy_v2_module and ngx_http_grpc_module. The flaw is reachable when NGINX is configured to proxy HTTP/2 traffic to upstreams using proxy_http_version 2 or grpc_pass, with ignore_invalid_headers set to off and large_client_header_buffers configured larger than 2 MB. Under those non-default conditions, a remote unauthenticated attacker can send oversized or malformed headers during upstream request creation, triggering memory corruption in the NGINX worker process. The immediate result is typically a worker crash and restart; on systems where ASLR is disabled, or where an attacker can otherwise bypass ASLR, the memory corruption may be leveraged for 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 valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.
All candidate exploits were filtered out by Mallory's validation.
Affected products & vendors
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Recent activity
42 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A second critical NGINX vulnerability affecting the ngx_http_proxy_v2_module and ngx_http_grpc_module, impacting HTTP/2 proxy and gRPC configurations under specific conditions.
A critical heap overflow vulnerability in NGINX HTTP/2-to-upstream or gRPC proxying that is triggered by malformed or oversized header content when permissive header handling and oversized header buffers are configured, potentially enabling denial of service or remote code execution.
A critical heap overflow in NGINX HTTP/2-to-upstream processing affecting proxy and gRPC paths under specific configuration conditions, with potential denial of service or remote code execution.
A critical heap-based buffer overflow vulnerability in NGINX proxy and gRPC modules tied to HTTP/2 upstream traffic, exploitable only under specific non-default configurations.
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Cross-references every affected SKU, including bundled OEM variants.
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