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CVE-2019-9511

Some HTTP/2 implementations are vulnerable to window size manipulation and stream prioritization manipulation, potentially leading to a denial of service

CVSS 3.0 High 7.5

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Description

Some HTTP/2 implementations are vulnerable to window size manipulation and stream prioritization manipulation, potentially leading to a denial of service. The attacker requests a large amount of data from a specified resource over multiple streams. They manipulate window size and stream priority to force the server to queue the data in 1-byte chunks. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.

Official description from the CVE record, published by certcc. Copyright © 1999-2026 The MITRE Corporation. See /security/cve/legal for the CVE license. View the record on cve.org

Key data

CVSS 3.0 High 7.5

Score published by certcc in the CVE record.

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Network

    The vulnerable component can be reached over a network, possibly from the Internet.

  • Attack complexity: Low

    No special conditions are needed. The attack can be repeated at will.

  • Privileges required: None

    No account or privileges are needed.

  • User interaction: None

    No action from any user is needed.

  • Scope: Unchanged

    The impact stays within the vulnerable component.

  • Confidentiality impact: None

    No effect on the secrecy of data.

  • Integrity impact: None

    No effect on the trustworthiness of data.

  • Availability impact: High

    Serious or total effect on availability.

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at first.org/cvss.

EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.
Score
0.59547 (59.5% probability)
Percentile
99.1%
Scores of
Nov 10, 2026
Model
v2026.06.15

Weakness (CWE)

CWE catalog version 5.0.
CWE names: Copyright © 2006-2026, The MITRE Corporation. See /security/cve/legal for the CWE license.
  • CWE-400Uncontrolled Resource Consumption

References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

Timeline

  1. ID reserved
  2. Record published
  3. Record last updated

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About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.
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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:49 UTC. Sources and licenses