CVE-2026-56434
Last modified
CVE-2026-56434 is a high-severity vulnerability rated 8.3/10 on the CVSS scale. NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. EPSS estimates a 0.45% chance of exploitation in the next 30 days.
Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| F5 | Nginx Gateway Fabric | >= 1.3.0, <= 1.6.2 |
| F5 | Nginx Gateway Fabric | >= 2.0.0, < 2.6.7 |
| F5 | Nginx Ingress Controller | >= 3.5.0, <= 3.7.2 |
| F5 | Nginx Ingress Controller | >= 5.0.0, < 5.5.3 |
| F5 | Nginx Ingress Controller | >= 2026-lts-r1, < 2026-lts-r4 |
| F5 | Nginx Ingress Controller | 4.0.0 |
| F5 | Nginx Ingress Controller | 4.0.1 |
| F5 | Nginx Plus | >= 37.0.0.1, < 37.0.3.1 |
| F5 | Nginx Plus | >= r33, < r36 |
| F5 | Nginx Plus | r36 |
| F5 | Waf | >= 4.11.0, <= 4.16.0 |
| F5 | Waf | >= 5.2.0, <= 5.8.0 |
| F5 | Waf | >= 5.9.0, < 5.13.4 |
References
- https://my.f5.com/manage/s/article/K000162098Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-56434?
How severe is CVE-2026-56434?
How do I fix CVE-2026-56434?
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-56422Multiple MISP core controllers and model capture paths accep…9.4
- CVE-2026-56423MISP Core contained broken access-control checks in the bulk…8.8
- CVE-2026-56424MISP core contained multiple broken access-control flaws whe…8.8
- CVE-2026-56425The Azure Active Directory (AAD) authentication implementati…8.8
- CVE-2026-56428The SSH service on BSH ELP (Electronic Platform) modules con…8.1
- CVE-2026-5643A vulnerability was identified in Cyber-III Student-Manageme…2.4
- CVE-2026-56437Uncontrolled search path element issue exists in Pupsman ver…8.4
- CVE-2026-5644A security flaw has been discovered in Cyber-III Student-Man…2.4
- CVE-2026-56444In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, whe…5.9
- CVE-2026-56445The qrscp application's C-STORE handler uses a specific inst…9.1
- CVE-2026-56446MISP allowed a site administrator to configure an arbitrary …7.2
- CVE-2026-56447MISP allowed an authenticated site administrator to set the …7.2
Are you affected by CVE-2026-56434?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST