CVE-2026-33186VulnerabilityPublished 2 Nov 2026

Red Hat Security Advisory: OpenShift Virtualization v4.17 Images

Affects Red HatSource GCVE Database

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Authoritative record:CVE-2026-33186· Critical 9.1

Not known to be exploited · CVSS 9.1 Critical : upgrade Red Hat grpc-go to 1.79.3 as a priority.

Data as of 3 Nov 2026, 04:43 UTC

CVSS 3.1 base score

9.1Critical

How severe the flaw is on the 0–10 CVSS scale.

Patch: Available – fixed in 1.79.3

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
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), the Metasploit, Exploit-DB and nuclei-templates index as of 2 Nov 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 grpc-go and github.com/grpc/grpc-go to 1.79.3.

Affected software

Product	Affected	Fixed in
grpcgrpc-go	Affected <1.79.3	Fixed in 1.79.3
Gogithub.com/grpc/grpc-go`pkg:golang/github.com/grpc/grpc-go`Other threats	Affected <1.79.3	Fixed in 1.79.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Red Hat advises implementing infrastructure-level normalization to ensure all incoming HTTP/2 :path headers include the mandatory leading slash before reaching the gRPC-Go server. This can be done by configuring and properly restarting a reverse proxy or API gateway to validate and normalize the :path header. Applying this mitigation may temporarily impact service availability.

Description

CVE-2026-33186 is an authorization bypass vulnerability in gRPC-Go caused by improper validation of the HTTP/2 :path pseudo-header. An attacker can send malformed :path headers without the mandatory leading slash to bypass path-based authorization policies. This affects Red Hat OpenShift Virtualization v4.17 images. The vulnerability is rated as important due to the potential for unauthorized access and information disclosure. Mitigation involves normalizing incoming :path headers at the infrastructure level, such as via a reverse proxy or API gateway.

Impact

Remote unauthenticated attackers can bypass path-based authorization controls by sending malformed HTTP/2 :path headers, potentially leading to unauthorized access to services or sensitive information disclosure. The impact is rated as important/high severity by Red Hat, with high confidentiality and integrity impact but no availability impact. The vulnerability compromises service integrity and confidentiality if exploited in environments using vulnerable authorization configurations.

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).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2026, 04:43 UTC

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-551

Technical details

References

Community reviews

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