CVE-2024-30156VulnerabilityPublished 21 May 2024Updated 5 Nov 2026

Red Hat Security Advisory: varnish:6 security update

Affects Red Hat varnish:6Source GCVE Database

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Authoritative record:CVE-2024-30156· High 7.5

Not known to be exploited · CVSS 7.5 High.

Data as of 5 Nov 2026, 14:17 UTC

CVSS 3.1 base score

7.5High

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

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 24 Mar 2024
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 5 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

AI-suggested

Red Hat has released updated varnish:6 packages for Red Hat Enterprise Linux 8.4 variants that address CVE-2024-30156. Users should apply these official updates as described in Red Hat advisory RHSA-2024:2938 and the referenced article https://access.redhat.com/articles/11258. Applying these updates will remediate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.

Description

A security vulnerability identified as CVE-2024-30156 affects Varnish Cache version 6, a high-performance HTTP accelerator. The flaw involves an HTTP/2 Broken Window Attack that may lead to denial of service. Red Hat has issued a security advisory and released updated packages for Red Hat Enterprise Linux 8.4 variants to address this issue. The vulnerability is rated as having an important security impact by Red Hat, with a high severity classification in this report. No CVSS score is provided in the available data. The vulnerability specifically affects Red Hat Enterprise Linux 8.4 distributions with varnish:6 module installed.

Impact

The vulnerability may result in denial of service conditions on systems running vulnerable versions of varnish:6, potentially disrupting web acceleration services. This could degrade website performance or availability relying on Varnish Cache. Red Hat rates the security impact as Important and the severity as high in this report. There is no indication of active exploitation in the wild.

Summary

CVE-2024-30156 is a denial of service vulnerability in Varnish Cache version 6 related to an HTTP/2 Broken Window Attack. Varnish Cache accelerates web servers by caching web pages in memory. This vulnerability may allow an attacker to disrupt service availability. Red Hat has released updated varnish:6 packages for multiple Red Hat Enterprise Linux 8.4 variants, including Extended Life Cycle Long Life, Update Services for SAP Solutions, AUS, and TUS. The advisory references Red Hat's errata RHSA-2024:2938 and provides package updates to mitigate the issue. No public exploit or CVSS score is currently documented. The fix is available in varnish-6.0.6-2.module+el8.4.0+21799+2c737c67.5 and related packages.

CWE-400Uncontrolled Resource Consumption (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product does not properly control the allocation and maintenance of a limited resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place.
Architecture and Design
Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or; uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Architecture and Design
Ensure that protocols have specific limits of scale placed on them.
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
XML Ping of the Death (opens in a new tab)
Regular Expression Exponential Blowup (opens in a new tab)
Sustained Client Engagement (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

Description

AI analysisMachine-generated, updated 5 Nov 2026, 14:17 UTC

WeaknessesCWE-400

Technical details

References

Community reviews

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