High 7.5Published Aug 13, 2019

CVE-2019-9511Some HTTP/2 implementations are vulnerable to window size manipulation and stream prioritization manipulation, potentially leading to a denial of service.

Updated under an hour ago (Nov 2, 2026, 12:23 AM ET)

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It affects apple swiftnio and 19 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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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.

CVSS: 7.5 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-400, CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Modified
Record last updated: Jun 16, 2026
First seen by InfoSec Signals: Nov 1, 2026

Affected products

Affected products

apple swiftnio apple:swiftnio	from 1.0.0 through 1.4.0	NVD
apache traffic_server apache:traffic_server	from 6.0.0 through 6.2.3; from 7.0.0 through 7.1.6; from 8.0.0 through 8.0.3	NVD
canonical ubuntu_linux canonical:ubuntu_linux	16.04; 18.04; 19.04	NVD
debian debian_linux debian:debian_linux	9.0; 10.0	NVD
synology skynas synology:skynas	all versions	NVD
synology diskstation_manager synology:diskstation_manager	6.2	NVD
synology vs960hd_firmware synology:vs960hd_firmware	all versions	NVD
fedoraproject fedora fedoraproject:fedora	29; 30	NVD
opensuse leap opensuse:leap	15.0; 15.1	NVD
redhat jboss_core_services redhat:jboss_core_services	1.0	NVD
1–10 of 20

References

References

http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00031.html	mailing-list, third-party-advisory
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00032.html	mailing-list, third-party-advisory
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00035.html	mailing-list, third-party-advisory
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00003.html	mailing-list, third-party-advisory
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00005.html	mailing-list, third-party-advisory
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00014.html	mailing-list, third-party-advisory
https://access.redhat.com/errata/RHSA-2019:2692	third-party-advisory
https://access.redhat.com/errata/RHSA-2019:2745	third-party-advisory
https://access.redhat.com/errata/RHSA-2019:2746	third-party-advisory
https://access.redhat.com/errata/RHSA-2019:2775	third-party-advisory
1–10 of 25

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.