CVE-2026-42926

5.8

MEDIUM CVSS 4.0

NGINX ngx_http_proxy_v2_module vulnerability

Overview

Description

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

Details

INFO

Published Date :

May 13, 2026, 4:16 p.m.

Last Modified :

May 13, 2026, 4:27 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]

Impact

Affected Products

The following products are affected by CVE-2026-42926 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID	Vendor	Product	Action
1	F5	nginx_open_source

: Total Affected Vendor : 1 | Products : 1

Scoring

CVSS Scores

The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.

Version	Severity	Source
CVSS 3.1	MEDIUM	9dacffd4-cb11-413f-8451-fbbfd4ddc0ab
CVSS 3.1	MEDIUM	[email protected]
CVSS 3.1	MEDIUM	MITRE-CVE
CVSS 4.0	MEDIUM	9dacffd4-cb11-413f-8451-fbbfd4ddc0ab
CVSS 4.0	MEDIUM	[email protected]

Solution

Update NGINX to patch the HTTP/2 frame header and payload injection vulnerability.

Update NGINX to the latest stable version.
Review and adjust proxy configurations.
Test for unexpected header behavior.

Public PoC/Exploit Available at Github

CVE-2026-42926 has a 2 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-42926.

URL	Resource
https://my.f5.com/manage/s/article/K000161131

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-42926 is associated with the following CWEs:

CWE-172: Encoding Error

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-42926 weaknesses.

CAPEC-3: Using Leading 'Ghost' Character Sequences to Bypass Input Filters Using Leading 'Ghost' Character Sequences to Bypass Input Filters CAPEC-52: Embedding NULL Bytes Embedding NULL Bytes CAPEC-53: Postfix, Null Terminate, and Backslash Postfix, Null Terminate, and Backslash CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic Using Slashes and URL Encoding Combined to Bypass Validation Logic CAPEC-71: Using Unicode Encoding to Bypass Validation Logic Using Unicode Encoding to Bypass Validation Logic CAPEC-72: URL Encoding URL Encoding CAPEC-78: Using Escaped Slashes in Alternate Encoding Using Escaped Slashes in Alternate Encoding CAPEC-80: Using UTF-8 Encoding to Bypass Validation Logic Using UTF-8 Encoding to Bypass Validation Logic CAPEC-120: Double Encoding Double Encoding CAPEC-267: Leverage Alternate Encoding Leverage Alternate Encoding

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

MateusVerass/nGixshell

nginx CVE scanner + RCE exploit framework (CVE-2026-42945 + 16 others)

Python

Updated: 2 weeks, 4 days ago

3 stars 3 fork 3 watcher

Born at : May 16, 2026, 2:25 p.m. This repo has been linked 53 different CVEs too.

lowphpcom/wnmp

WNMP One‑Click Stack | WebDAV · Nginx · PHP · MariaDB · Kernel Tuning

Shell

Updated: 2 weeks, 6 days ago

26 stars 4 fork 4 watcher

Born at : Dec. 7, 2025, 11:39 p.m. This repo has been linked 6 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-42926 vulnerability anywhere in the article.

Daily CyberSecurity

Nginx Releases Critical Update: Six Vulnerabilities Patched in New Stable Version

The web infrastructure world received a major wake-up call today as nginx-1.30.1 was released to address a suite of six security vulnerabilities. These flaws range from high-severity arbitrary code ex ...

Published Date: May 14, 2026 (3 weeks, 1 day ago)

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-42926 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

New CVE Received by [email protected]

May. 13, 2026

Action	Type	New Value
Added	Description	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 reached End of Technical Support (EoTS) are not evaluated.
Added	CVSS V4.0	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
Added	CVSS V3.1	AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Added	CWE	CWE-172
Added	Reference	https://my.f5.com/manage/s/article/K000161131

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.