CVE-2026-4800VulnerabilityPublished 20 May 2026Updated 30 Oct 2026

Red Hat Security Advisory: OpenShift Container Platform 4.18.42 bug fix and security update

Affects Red HatSource GCVE Database

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Mentioned vulnerabilities

CVE-2026-33186

Not known to be exploited : upgrade Red Hat to 4.18.42 soon.

Data as of 30 Oct 2026, 11:52 UTC

Severity

High

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 2.8% chance of exploitation in 30 days – higher than 86% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.18.42

Exploitation evidence

Disclosed: evidence found.
CVE published 20 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Red Hat to 4.18.42.

Affected software

Product	Affected	Fixed in
Red Hat Product Security Red Hat	Affected >=4.18.0 <4.18.42 Red Hat Red Hat OpenShift Container Platform Red Hat OpenShift Container Platform 4.18 arm64 registry.redhat.io/openshift4/ose-azure-file-csi-driver-operator-rhel9@sha256:6581ddd902d56312a4915019c5e01deed3f14ffbad508d9f8572fdd9137dd931_arm64	Fixed in 4.18.42

AI-suggested

Red Hat has released OpenShift Container Platform 4.18.42 containing fixes for this vulnerability and other issues. Users should upgrade to version 4.18.42 using the official upgrade instructions provided by Red Hat. Additionally, to mitigate CVE-2026-33186, infrastructure-level normalization of HTTP/2 :path headers is recommended, such as configuring reverse proxies or API gateways to validate and normalize the :path header before it reaches the gRPC-Go server. This update is available via the appropriate release channels and can be applied using the OpenShift CLI or web console.

Description

Red Hat OpenShift Container Platform is Red Hat's cloud computing Kubernetes application platform solution designed for on-premise or private cloud deployments. This advisory contains the container images for Red Hat OpenShift Container Platform 4.18.42. See the following advisory for the RPM packages for this release: https://access.redhat.com/errata/RHSA-2026:17446 Space precludes documenting all of the container images in this advisory. See the following Release Notes documentation, which will be updated shortly for this release, for details about these changes: https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html/release_notes/

Impact

The primary impact is an authorization bypass in gRPC-Go that could allow remote attackers to circumvent security policies and gain unauthorized access to services or sensitive information. This affects deployments of OpenShift Container Platform that use the vulnerable gRPC-Go component. The vulnerability has a CVSS v3 base score of 9.1 (Red Hat rating), indicating high severity with high confidentiality and integrity impact but no availability impact. No known exploits in the wild have been reported at this time.

Summary

This advisory covers Red Hat OpenShift Container Platform 4.18.42, which contains fixes for several bugs and security vulnerabilities. Notably, CVE-2026-33186 is an authorization bypass vulnerability in the gRPC-Go implementation due to improper validation of the HTTP/2 :path pseudo-header. Attackers can exploit this by sending malformed :path headers lacking the mandatory leading slash, potentially bypassing authorization controls and accessing unauthorized services or information. The update includes container image updates and RPM package fixes. Red Hat rates the security impact of this update as Important (high severity).

CWE-94Improper Control of Generation of Code (Code Injection) (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #10OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
Architecture and Design · Refactoring
Refactor your program so that you do not have to dynamically generate code.
Architecture and Design
Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V5.2.8 (opens in a new tab)
V5.2.5 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
Leverage Executable Code in Non-Executable Files (opens in a new tab)
Manipulating User-Controlled Variables (opens in a new tab)
Code Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-551Incorrect Behavior Order: Authorization Before Parsing and Canonicalization (opens in a new tab)
Base weakness
If a web server does not fully parse requested URLs before it examines them for authorization, it may be possible for an attacker to bypass authorization protection.
Architecture and Design
URL Inputs should be decoded and canonicalized to the application's current internal representation before being validated and processed for authorization. Make sure that your application does not decode the same input twice.
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
V7.2.2 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-835Loop with Unreachable Exit Condition (Infinite Loop) (opens in a new tab)
Base weakness
The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.
CWE-131Incorrect Calculation of Buffer Size (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product does not correctly calculate the size to be used when allocating a buffer.
Implementation
When allocating a buffer for the purpose of transforming, converting, or encoding an input, allocate enough memory to handle the largest possible encoding. For example, in a routine that converts "&" characters to "&" for HTML entity encoding, the output buffer needs to be at least 5 times as large as the input…
Implementation
Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how the language handles…
Implementation · Input Validation
Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
Attack patterns
Overflow Buffers (opens in a new tab)
Buffer Overflow via Parameter Expansion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Aug 2026, 17:20 UTC

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-94, CWE-551, CWE-835 +1

Technical details

References

Community reviews

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