# CVE-2026-42055: NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module vulnerability > Remote attackers can trigger heap-based buffer overflows in NGINX via large headers, potentially causing service restarts or arbitrary code execution. - **Severity:** Critical 9.2 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 17 Jun 2026 - **Updated:** 14 Sep 2026 - **Also known as:** ALPINE-CVE-2026-42055, ALSA-2026:36331, ALSA-2026:36364, ALSA-2026:36618, ALSA-2026:36639, ALSA-2026:38847, AZL-91419, BELL-CVE-2026-42055, BIT-nginx-2026-42055, BIT-nginx-gateway-2026-42055, BIT-nginx-gateway-fabric-2026-42055, CLSA-2026-1783696553, CLSA-2026-1784714136, CLSA-2026-1784714329, CLSA-2026-1784714664, CLSA-2026-1784807256, CLSA-2026-1785845612, CLSA-2026-1790152715, CLSA-2026-1791460658, DEBIAN-CVE-2026-42055, ECHO-9157-e0cb-829d, GHSA-78jw-ww3g-9wp7, MINI-6vc5-946p-4683, MINI-cc2c-539f-h36r, MINI-f9f2-hh8p-rgf6, MINI-jhfq-rrgx-m8gf, MINI-mf8g-v3ff-j85r, MINI-v3cg-8fc7-c3qm, RHSA-2026:36331, RHSA-2026:36364, RHSA-2026:36618, RHSA-2026:36639, RHSA-2026:38847, RLSA-2026:36331, RLSA-2026:36364, RLSA-2026:36618, RLSA-2026:36639, RLSA-2026:38847, UBUNTU-CVE-2026-42055 ## What is CVE-2026-42055? CVE-2026-42055 is a critical memory corruption vulnerability in Redhat Enterprise Linux, published on 17 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official 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. Weakness: CWE-787 (Out-of-bounds Write), CWE-131 (Incorrect Calculation of Buffer Size), CWE-122 (Heap-based Buffer Overflow) ## Which versions are affected by CVE-2026-42055? 3 open source packages ship an affected version, including nginx, nginx-gateway and nginx-gateway-fabric. It affects 11 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `nginx` | Bitnami | From 1.30.0 | 1.30.3, 1.31.2 | | `nginx-gateway` | Bitnami | From 1.30.0 | 1.30.3, 1.31.2 | | `nginx-gateway-fabric` | Bitnami | From 1.3.0 | 2.6.4 | | `nginx` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-all-modules` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-core` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-filesystem` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-mod-devel` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-mod-http-image-filter` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-mod-http-perl` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-mod-http-xslt-filter` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-mod-mail` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx-mod-stream` | AlmaLinux:10 | All versions | 2:1.26.3-6.el10_2.5 | | `nginx` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx-all-modules` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx-filesystem` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx-mod-devel` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx-mod-http-image-filter` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx-mod-http-perl` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx-mod-http-xslt-filter` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx-mod-mail` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx-mod-stream` | AlmaLinux:8 | All versions | 1:1.24.0-3.module_el8.10.0+4215+c88f2fa5.3.alma.1 | | `nginx` | AlmaLinux:9 | All versions | 1:1.24.0-7.module_el9.8.0+278+b57266e8.3.alma.1 | | `nginx` | AlmaLinux:9 | All versions | 2:1.20.1-28.el9_8.4.alma.1 | | `nginx` | AlmaLinux:9 | All versions | 2:1.26.3-9.module_el9.8.0+281+75d5e6d4.2 | | `nginx-all-modules` | AlmaLinux:9 | All versions | 1:1.24.0-7.module_el9.8.0+278+b57266e8.3.alma.1 | | `nginx-all-modules` | AlmaLinux:9 | All versions | 2:1.20.1-28.el9_8.4.alma.1 | | `nginx-all-modules` | AlmaLinux:9 | All versions | 2:1.26.3-9.module_el9.8.0+281+75d5e6d4.2 | | `nginx-core` | AlmaLinux:9 | All versions | 1:1.24.0-7.module_el9.8.0+278+b57266e8.3.alma.1 | | `nginx-core` | AlmaLinux:9 | All versions | 2:1.20.1-28.el9_8.4.alma.1 | | `nginx-core` | AlmaLinux:9 | All versions | 2:1.26.3-9.module_el9.8.0+281+75d5e6d4.2 | | `nginx-filesystem` | AlmaLinux:9 | All versions | 1:1.24.0-7.module_el9.8.0+278+b57266e8.3.alma.1 | | `nginx-filesystem` | AlmaLinux:9 | All versions | 2:1.20.1-28.el9_8.4.alma.1 | | `nginx-filesystem` | AlmaLinux:9 | All versions | 2:1.26.3-9.module_el9.8.0+281+75d5e6d4.2 | | `nginx-mod-devel` | AlmaLinux:9 | All versions | 1:1.24.0-7.module_el9.8.0+278+b57266e8.3.alma.1 | | `nginx-mod-devel` | AlmaLinux:9 | All versions | 2:1.20.1-28.el9_8.4.alma.1 | | `nginx-mod-devel` | AlmaLinux:9 | All versions | 2:1.26.3-9.module_el9.8.0+281+75d5e6d4.2 | | `nginx-mod-http-image-filter` | AlmaLinux:9 | All versions | 1:1.24.0-7.module_el9.8.0+278+b57266e8.3.alma.1 | | `nginx-mod-http-image-filter` | AlmaLinux:9 | All versions | 2:1.20.1-28.el9_8.4.alma.1 | | `nginx-mod-http-image-filter` | AlmaLinux:9 | All versions | 2:1.26.3-9.module_el9.8.0+281+75d5e6d4.2 | Products: F5 Dos, F5 Nginx Gateway Fabric, F5 Nginx Ingress Controller, F5 Nginx Instance Manager, F5 Nginx Open Source, F5 Nginx Plus, F5 Waf, Redhat Discovery, Redhat Enterprise Linux, Redhat Hardened Images, Redhat Update Infrastructure. ## How do I fix CVE-2026-42055? Upgrade nginx to a fixed version for your release line: 1.30.3 or 1.31.2. ## Is CVE-2026-42055 being exploited? There is no known exploitation of CVE-2026-42055 in the wild and no public exploit code. Public exploit code: - CVE-2026-42055 - Draft (github_poc): https://github.com/HORKimhab/CVE-2026-42055 ## Other vulnerabilities in Redhat Enterprise Linux - [CVE-2026-42945](https://insights.sbomify.com/CVE-2026-42945/): NGINX ngx_http_rewrite_module vulnerability (critical 9.2) - [CVE-2026-42946](https://insights.sbomify.com/CVE-2026-42946/): NGINX ngx_http_scgi_module and ngx_http_uwsgi_module vulnerability (high 8.3) - [CVE-2026-40460](https://insights.sbomify.com/CVE-2026-40460/): NGINX ngx_quic_module vulnerability (medium 6.9) - [CVE-2026-48142](https://insights.sbomify.com/CVE-2026-48142/): NGINX ngx_http_charset_module vulnerability (medium 6.3) - [CVE-2026-40701](https://insights.sbomify.com/CVE-2026-40701/): NGINX ngx_http_ssl_module vulnerability (medium 6.3) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-42055 and fix it if it is affected. What it is: CVE-2026-42055 is a critical memory corruption vulnerability in Redhat Enterprise Linux, published on 17 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-42055 in the wild and no public exploit code. Affected packages and fixed versions: - nginx (Bitnami): affected from 1.30.0; fixed in 1.30.3, 1.31.2 - nginx-gateway (Bitnami): affected from 1.30.0; fixed in 1.30.3, 1.31.2 - nginx-gateway-fabric (Bitnami): affected from 1.3.0; fixed in 2.6.4 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-42055/ (Markdown: https://insights.sbomify.com/CVE-2026-42055/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42055 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42055 - OSV: https://osv.dev/vulnerability/CVE-2026-42055 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-42055/ Summaries are generated and may contain mistakes; the official description above is the record.