Critical
Security advisory
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-42055
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 06:03 UTC · Revision 1
Source evidence
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.
osv:CVE-2026-42055
Complete source record
{
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"url": "https://osv.dev/vulnerability/CVE-2026-42055",
"method": "structured",
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"title": "CVE-2026-42055",
"summary": "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.",
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"modified": "2026-10-24T10:30:34.737664257Z",
"provider": "osv",
"references": [
"https://access.redhat.com/errata/RHSA-2026:27197",
"https://access.redhat.com/errata/RHSA-2026:36331",
"https://access.redhat.com/errata/RHSA-2026:36364",
"https://access.redhat.com/errata/RHSA-2026:36618",
"https://access.redhat.com/errata/RHSA-2026:36639",
"https://access.redhat.com/errata/RHSA-2026:38847",
"https://access.redhat.com/errata/RHSA-2026:44481",
"https://access.redhat.com/errata/RHSA-2026:46836",
"https://access.redhat.com/errata/RHSA-2026:58981",
"https://access.redhat.com/security/cve/CVE-2026-42055",
"https://my.f5.com/manage/s/article/K000161584",
"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42055.json",
"https://bugzilla.redhat.com/show_bug.cgi?id=2489866"
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}