CVE-2024-30156Network attack vector

Denial of service via HTTP/2 credit exhaustion

Published Mar 24, 2024 · Updated Nov 21, 2024

Denial of service in affected Varnish Cache and Varnish Enterprise releases allows remote attackers to stall HTTP/2 streams. The server permits an HTTP/2 connection's flow-control window to remain indefinitely out of credits, preventing stream progress while retaining associated resources. HTTP/2 must be enabled, and accumulated stalled streams can exhaust server resources and interrupt cache service without affecting data confidentiality or integrity.

CVSS severity7.5
High
EPSS probability3.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected Varnish Cache and Varnish Enterprise releases allows remote attackers to stall HTTP/2 streams. The server permits an HTTP/2 connection's flow-control window to remain indefinitely out of credits, preventing stream progress while retaining associated resources. HTTP/2 must be enabled, and accumulated stalled streams can exhaust server resources and interrupt cache service without affecting data confidentiality or integrity.

The record

CVE
CVE-2024-30156
Published
Mar 24, 2024
Updated
Nov 21, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 24, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 21, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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