CVE-2026-56434

NGINX ngx_http_ssi_module vulnerability

MEDIUM

6.5

CVSS Score

Published: July 15, 2026 at 02:33 PM UTC

Updated: August 10, 2026 at 03:38 PM UTC

5 products affected across 1 vendorNGINX PlusNGINX Ingress ControllerNGINX Gateway Fabric

Using NGINX Plus by F5?

Get instant alerts when new vulnerabilities affect NGINX Plus - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

MEDIUM6.5

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

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 heap buffer over-read 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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

NGINX Gateway Fabric · F5

95%

1.3.0 ≤ v ≤ 1.6.22.0.0 ≤ v < 2.6.7

Affected range stops below 2.6.7, so it looks safe — our inference, not a vendor statement

NGINX Ingress Controller · F5

95%

2026-lts-r1 ≤ v < 2026-lts-r43.5.0 ≤ v ≤ 3.7.25.0.0 ≤ v < 5.5.34.0.0 4.0.1

Affected range stops below 2026-lts-r4, so it looks safe — our inference, not a vendor statement

Affected range stops below 5.5.3, so it looks safe — our inference, not a vendor statement

NGINX Plus · F5

95%

v ≥ R3337.0.0.1 ≤ v < 37.0.3.1R36 ≤ v < R36 P7r33 ≤ v < r3637.0.0.1 R33 R36 r36 r36 p1 r36 p2 r36 p3 r36 p4 r36 p5 r36 p6

Affected range stops below 37.0.3.1, so it looks safe — our inference, not a vendor statement

Affected range stops below R36 P7, so it looks safe — our inference, not a vendor statement

Affected range stops below r36, so it looks safe — our inference, not a vendor statement

Waf · F5

95%

4.11.0 ≤ v ≤ 4.16.05.2.0 ≤ v ≤ 5.8.05.9.0 ≤ v < 5.13.4

Affected range stops below 5.13.4, so it looks safe — our inference, not a vendor statement

NGINX Open Source · F5

60%

0.8.11 ≤ v < 1.30.41.31.2 ≤ v < 1.31.30.8.11 1.31.2

Affected range stops below 1.30.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 1.31.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://my.f5.com/manage/s/article/K000162098

References (1)

Vendor AdvisoryPatch

Source: cverecord

https://my.f5.com/manage/s/article/K000162098

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMf5

Attack Vector: NETWORK
Complexity: HIGH
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: LOW
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-416

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create account Sign in

Free plan, no card