CVE-2019-9511
HIGHEPSS 99th pctlDescription
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.
How to fix
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 99% of all known CVEs.
References
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- lists.opensuse.org
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- access.redhat.com
- github.com
- kb.cert.org
- kc.mcafee.com
- seclists.org
- seclists.org
- security.netapp.com
- security.netapp.com
- support.f5.com
- usn.ubuntu.com
- debian.org
- debian.org
- debian.org
- oracle.com
- oracle.com
- synology.com
Related Vulnerabilities
Other CWE-400 (Resource Exhaustion) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-44487 | High | 7.5 | 100% | KEV | Fix |
| CVE-2021-44228 | Critical | 10.0 | 100% | KEV + Ransom | Fix |
| CVE-2011-3192 | High | 7.8 | 99% | - | Fix |
| CVE-2019-11478 | Medium | 5.3 | 95% | - | Fix |
| CVE-2023-21547 | High | 7.5 | 89% | - | Fix |
| CVE-2018-1000115 | High | 7.5 | 88% | - | Fix |
Common questions
How do I fix CVE-2019-9511?
Published advisories record a fix for 50 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2019-9511 being actively exploited?
Not that we know of. CVE-2019-9511 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 59.5% is the estimated probability that it will be exploited in the next 30 days. That is higher than 99% of all scored CVEs.
How severe is CVE-2019-9511?
CVE-2019-9511 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2019-9511 affect?
Published advisories record a fix for libnghttp2 (Amazon), libnghttp2-devel (Amazon), mod_http2 (Amazon), mod_http2-debuginfo (Amazon), and 46 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-17.