CVE-2026-42055
Analyzed
Analyzed - Analysis Complete
Heap-based Buffer Overflow in NGINX Plus and NGINX Open Source
Vulnerability report for CVE-2026-42055, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-06-17
Last updated on: 2026-07-02
Assigner: F5 Networks
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| f5 | nginx_plus | r30 |
| f5 | nginx_plus | r31 |
| f5 | nginx_plus | r30 |
| f5 | nginx_plus | r31 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r30 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r33 |
| f5 | nginx_plus | r33 |
| f5 | nginx_plus | r33 |
| f5 | nginx_plus | r34 |
| f5 | nginx_plus | r34 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r33 |
| f5 | nginx_plus | r34 |
| f5 | nginx_plus | r35 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r35 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r32 |
| f5 | nginx_app_protect_dos | From 4.3.0 (inc) to 4.7.0 (inc) |
| f5 | nginx_gateway_fabric | From 1.3.0 (inc) to 1.6.2 (inc) |
| f5 | nginx_ingress_controller | From 3.5.0 (inc) to 3.7.2 (inc) |
| f5 | dos | 4.9.0 |
| f5 | nginx_instance_manager | From 2.17.0 (inc) to 2.22.0 (inc) |
| f5 | nginx_plus | From 37.0.0 (inc) to 37.0.1 (inc) |
| f5 | waf | From 5.9.0 (inc) to 5.13.1 (inc) |
| f5 | nginx_gateway_fabric | From 2.0.0 (inc) to 2.6.4 (exc) |
| f5 | nginx_ingress_controller | From 5.0.0 (inc) to 5.5.1 (exc) |
| f5 | nginx_ingress_controller | 4.0.0 |
| f5 | nginx_ingress_controller | 4.0.1 |
| f5 | nginx_app_protect_waf | From 4.10.0 (inc) to 4.16.0 (inc) |
| f5 | nginx_app_protect_waf | From 5.2.0 (inc) to 5.8.0 (inc) |
| f5 | nginx_open_source | From 1.30.0 (inc) to 1.30.3 (exc) |
| f5 | nginx_open_source | 1.31.1 |
| f5 | nginx_plus | r3 |
| f5 | nginx_plus | r31 |
| f5 | nginx_plus | r31 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | waf | 4.8.1 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-131 | The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow. |
| CWE-122 | A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). |
| CWE-787 | The product writes data past the end, or before the beginning, of the intended buffer. |
