CVE-2026-33818VulnerabilityPublished 2 Nov 2026

Red Hat Security Advisory: OpenShift Virtualization v4.16 Images

Affects Red HatSource GCVE Database

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Authoritative record:CVE-2026-33818· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in Red Hat package updates : patch Red Hat asn1 soon.

Data as of 3 Nov 2026, 04:45 UTC

CVSS 3.1 base score

7.5High

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

Thin evidence

One scorer or none

CVSS scores by source
CISA-ADP	CVSS 3.1	7.5

Patch: Available – fixed in 1.27.0-rc.3, 1.26.6, 1.25.13

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

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

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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Aug 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 encoding/asn1 to 1.27.0-rc.3, 1.26.6 or 1.25.13.

Affected software

Product	Affected	Fixed in
Go standard libraryencoding/asn1	Affected >=1.27.0-0 <1.27.0-rc.3	Fixed in 1.27.0-rc.3
Go standard libraryencoding/asn1	Affected >=1.26.0-0 <1.26.6	Fixed in 1.26.6
Go standard libraryencoding/asn1	Affected <1.25.13	Fixed in 1.25.13
Goencoding/asn1`pkg:golang/encoding/asn1`Other threats	Affected <1.25.13 >=1.26.0-0 <1.26.6 >=1.27.0-0 <1.27.0-rc.3	Fixed in 1.25.13 1.26.6 1.27.0-rc.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 currently states that no mitigation is available or that existing options do not meet their criteria for ease of use, deployment, applicability, or stability. Customers with Red Hat Technical Account Managers can seek direct guidance. No urgent remediation steps beyond applying existing errata are currently recommended.

Description

CVE-2026-33818 is a denial of service vulnerability in the Go programming language's encoding/asn1 package. It arises from excessive recursion triggered by a specially crafted, deeply nested ASN.1 structure during the Unmarshal operation. This flaw can be exploited remotely without authentication, potentially causing stack exhaustion and rendering services unavailable. Red Hat's OpenShift Virtualization v4.16 images include this vulnerability. Currently, no effective mitigation or patch meeting Red Hat's criteria is available.

Impact

The vulnerability can be triggered remotely without authentication by providing a malformed ASN.1 structure, causing excessive recursion and stack exhaustion during the Unmarshal operation. This results in a denial of service condition, making affected services unavailable. There is no impact on confidentiality or integrity reported. The flaw affects availability with a high severity rating by Red Hat.

Summary

A flaw in Go's encoding/asn1 package allows an attacker to supply a maliciously crafted ASN.1 structure that causes excessive recursion during unmarshalling. This leads to stack exhaustion and a denial of service condition. The vulnerability affects Red Hat OpenShift Virtualization v4.16 images. The issue is remotely exploitable without authentication. Red Hat has classified this as an Important security advisory with a high impact on availability.

CWE-776Improper Restriction of Recursive Entity References in DTDs (Billion Laughs Attack) (opens in a new tab)
Base weaknessLikelihood of exploit: MediumOWASP Top 10 A02:2025: Security Misconfiguration (opens in a new tab)
The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities.
Operation
If possible, prohibit the use of DTDs or use an XML parser that limits the expansion of recursive DTD entities.
Implementation
Before parsing XML files with associated DTDs, scan for recursive entity declarations and do not continue parsing potentially explosive content.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
Exponential Data 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 3 Nov 2026, 04:45 UTC

WeaknessesCWE-776

Technical details

References

Community reviews

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