Cyber Resilience

CVE-2026-42926

F5 Nginx Ingress Controller 3.5.0 – 3.7.2

Published
13 May 2026
Modified
18 June 2026
Patch / advisory
View advisory
CVSS Score v4 6.3
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/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
EPSS Score 0.0035 27th percentile
Risk Priority 39 floored blend · peak EPSS

Summary

CVE-2026-42926 is a medium-severity Encoding Error (CWE-172) vulnerability in F5 Nginx Ingress Controller. Its CVSS base score is 6.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 27th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SI-15 (Information Output Filtering) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

When NGINX Open Source is configured to proxy HTTP/2 traffic by setting proxy_http_version to 2, and also uses proxy_set_body, an attacker may be able to inject frame headers and payload bytes to the upstream peer. Note: Software versions which have…

more

reached End of Technical Support (EoTS) are not evaluated.

CWE(s)
CWE-172

Related Threats

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1027 Obfuscated Files or Information Stealth
Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit.
attack.mitre.org →
T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-42530Same product: F5 Nginx Gateway Fabric
CVE-2026-1642Same product: F5 Nginx Gateway Fabric
CVE-2026-42945Same product: F5 Nginx Gateway Fabric
CVE-2026-40701Same product: F5 Nginx Gateway Fabric
CVE-2026-42934Same product: F5 Nginx Gateway Fabric
CVE-2026-48142Same product: F5 Nginx Gateway Fabric
CVE-2026-42946Same product: F5 Nginx Gateway Fabric
CVE-2026-60005Same product: F5 Nginx Gateway Fabric
CVE-2026-40460Same product: F5 Nginx Gateway Fabric
CVE-2026-56434Same product: F5 Nginx Gateway Fabric

Affected Assets

f5
nginx gateway fabric
1.3.0 — 1.6.2 · 2.0.0 — 2.6.0
f5
nginx open source
1.29.4 — 1.30.0
f5
nginx instance manager
2.16.0 — 2.22.0
f5
nginx ingress controller
3.5.0 — 3.7.2 · 4.0.0 — 4.0.1 · 5.0.0 — 5.4.2

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation partial match

Input validation can reject or normalize improperly encoded data before it is processed.

SI-15 Information Output Filtering partial match

Output filtering enforces correct encoding or escaping of data leaving the system.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require correct data encoding to avoid injection and corruption flaws.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.28 Secure coding mostly match
degrades

Secure coding explicitly requires correct character encoding and output escaping to avoid CWE-172.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect encoding flaws before deployment.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle includes input/output validation and encoding practices that reduce encoding errors.

A.8.26 Application security requirements partial match
prevents

Application security requirements can mandate proper encoding/decoding to prevent data corruption or injection.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture and engineering principles address data handling and transformation correctness.

References