CVE-2024-30156VulnerabilityPublished 8 Apr 2024Updated 5 Nov 2026

Red Hat Security Advisory: rh-varnish6-varnish security update

Affects Red Hat rh-varnish6-varnishSource 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, 14:18 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 rh-varnish6-varnish packages for Red Hat Software Collections on RHEL 7 to address this vulnerability. Users should apply the official security update as described in Red Hat advisory RHSA-2024:1689 and the referenced article https://access.redhat.com/articles/11258. This update fixes the vulnerability and mitigates the risk of denial of service. No additional mitigation steps are indicated by the vendor.

Description

A security update for rh-varnish6-varnish addresses a vulnerability identified as CVE-2024-30156, which involves an HTTP/2 Broken Window Attack that may lead to denial of service. This vulnerability affects Varnish Cache, a high-performance HTTP accelerator used to speed up web servers by caching web pages in memory. The update is rated as important by Red Hat and is available for Red Hat Software Collections on RHEL 7 for various architectures. The advisory provides instructions for applying the update to mitigate the issue.

Impact

The vulnerability may allow an attacker to cause a denial of service condition via the HTTP/2 Broken Window Attack against Varnish Cache. This could disrupt the availability of web services accelerated by Varnish. No information about privilege escalation or data compromise is provided. The impact is limited to denial of service.

Summary

CVE-2024-30156 is a vulnerability in Varnish Cache related to the HTTP/2 Broken Window Attack, which can cause denial of service. Varnish Cache accelerates HTTP traffic by caching web content in memory. Red Hat has issued a security advisory (RHSA-2024:1689) for rh-varnish6-varnish packages in Red Hat Software Collections on RHEL 7, providing updated packages to fix this issue. The advisory rates the impact as important and directs users to apply the update to remediate the vulnerability. No CVSS score is provided in the advisory, and no known exploits in the wild have been reported.

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).

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 5 Nov 2026, 14:18 UTC

WeaknessesCWE-400

Technical details

References

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