CVE-2019-9518
Synology
- Published
- 13 August 2019
- Last modified
- 17 June 2026
- CVSS
- 7.5 v3.1
- Severity
- high
- EPSS
- 25.4% (98th pct)
- CISA KEV
- Not listed
- NVD status
- Modified
- Weaknesses
- CWE-400, CWE-770
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Description
Some HTTP/2 implementations are vulnerable to a flood of empty frames, potentially leading to a denial of service. The attacker sends a stream of frames with an empty payload and without the end-of-stream flag. These frames can be DATA, HEADERS, CONTINUATION and/or PUSH_PROMISE. The peer spends time processing each frame disproportionate to attack bandwidth. This can consume excess CPU.
Exploitation
Not listed in the CISA Known Exploited Vulnerabilities catalogue as of 2026.09.04. That is an absence of confirmed public exploitation, not evidence that exploitation has not occurred. EPSS models a 25.4% probability of exploitation activity in the next 30 days, placing it in the top decile of all scored CVEs.
Affected products
| Product | Vendor | Type | Versions named |
|---|---|---|---|
| VS960HD | Synology | unknown | < 2.2.3-1505, < 2.3.6-1720 |
References
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00031.html third-party
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00032.html third-party
- http://seclists.org/fulldisclosure/2019/Aug/16 third-party
- https://access.redhat.com/errata/RHSA-2019:2925 third-party
- https://access.redhat.com/errata/RHSA-2019:2939 third-party
- https://access.redhat.com/errata/RHSA-2019:2955 third-party
- https://access.redhat.com/errata/RHSA-2019:3892 third-party
- https://access.redhat.com/errata/RHSA-2019:4352 third-party
- https://access.redhat.com/errata/RHSA-2020:0727 third-party
- https://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-002.md third-party
- https://kb.cert.org/vuls/id/605641/ third-party
- https://kc.mcafee.com/corporate/index?page=content&id=SB10296 third-party
- https://lists.apache.org/thread.html/091b518265bce56a16af87b77c8cfacda902a02079e866f9fdf13b61%40%3Cusers.trafficserver.apache.org%3E
- https://lists.apache.org/thread.html/2653c56545573b528f3f6352a29eccaf498bd6fb2a6a59568d81a61d%40%3Cannounce.trafficserver.apache.org%3E
- https://lists.apache.org/thread.html/9317fd092b257a0815434b116a8af8daea6e920b6673f4fd5583d5fe%40%3Ccommits.druid.apache.org%3E
- https://lists.apache.org/thread.html/ff5b0821a6985159a832ff6d1a4bd311ac07ecc7db1e2d8bab619107%40%3Cdev.trafficserver.apache.org%3E
- https://lists.apache.org/thread.html/r99a625fb17032646d96cd23dec49603ff630e9318e44a686d63046bc%40%3Ccommits.cassandra.apache.org%3E
- https://lists.apache.org/thread.html/rd31230d01fa6aad18bdadc0720acd1747e53690bd35f73a48e7a9b75%40%3Ccommits.cassandra.apache.org%3E
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4ZQGHE3WTYLYAYJEIDJVF2FIGQTAYPMC/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CMNFX5MNYRWWIMO4BTKYQCGUDMHO3AXP/
- https://seclists.org/bugtraq/2019/Aug/24 third-party
- https://seclists.org/bugtraq/2019/Sep/18 third-party
- https://security.netapp.com/advisory/ntap-20190823-0005/ third-party
- https://support.f5.com/csp/article/K46011592 third-party
- https://support.f5.com/csp/article/K46011592?utm_source=f5support&%3Butm_medium=RSS
- https://www.debian.org/security/2019/dsa-4520 third-party
- https://www.synology.com/security/advisory/Synology_SA_19_33 third-party
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00031.html third-party
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00032.html third-party
- http://seclists.org/fulldisclosure/2019/Aug/16 third-party
- https://access.redhat.com/errata/RHSA-2019:2925 third-party
- https://access.redhat.com/errata/RHSA-2019:2939 third-party
- https://access.redhat.com/errata/RHSA-2019:2955 third-party
- https://access.redhat.com/errata/RHSA-2019:3892 third-party
- https://access.redhat.com/errata/RHSA-2019:4352 third-party
- https://access.redhat.com/errata/RHSA-2020:0727 third-party
- https://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-002.md third-party
- https://kb.cert.org/vuls/id/605641/ third-party
- https://kc.mcafee.com/corporate/index?page=content&id=SB10296 third-party
- https://lists.apache.org/thread.html/091b518265bce56a16af87b77c8cfacda902a02079e866f9fdf13b61%40%3Cusers.trafficserver.apache.org%3E
- https://lists.apache.org/thread.html/2653c56545573b528f3f6352a29eccaf498bd6fb2a6a59568d81a61d%40%3Cannounce.trafficserver.apache.org%3E
- https://lists.apache.org/thread.html/9317fd092b257a0815434b116a8af8daea6e920b6673f4fd5583d5fe%40%3Ccommits.druid.apache.org%3E
- https://lists.apache.org/thread.html/ff5b0821a6985159a832ff6d1a4bd311ac07ecc7db1e2d8bab619107%40%3Cdev.trafficserver.apache.org%3E
- https://lists.apache.org/thread.html/r99a625fb17032646d96cd23dec49603ff630e9318e44a686d63046bc%40%3Ccommits.cassandra.apache.org%3E
- https://lists.apache.org/thread.html/rd31230d01fa6aad18bdadc0720acd1747e53690bd35f73a48e7a9b75%40%3Ccommits.cassandra.apache.org%3E
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4ZQGHE3WTYLYAYJEIDJVF2FIGQTAYPMC/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CMNFX5MNYRWWIMO4BTKYQCGUDMHO3AXP/
- https://seclists.org/bugtraq/2019/Aug/24 third-party
- https://seclists.org/bugtraq/2019/Sep/18 third-party
- https://security.netapp.com/advisory/ntap-20190823-0005/ third-party
- https://support.f5.com/csp/article/K46011592 third-party
- https://support.f5.com/csp/article/K46011592?utm_source=f5support&%3Butm_medium=RSS
- https://www.debian.org/security/2019/dsa-4520 third-party
- https://www.synology.com/security/advisory/Synology_SA_19_33 third-party
Record assembled from NVD, CISA KEV 2026.09.04 and FIRST EPSS 2026-09-04. Affected products are those NVD's CPE configuration names that fall inside this site's scope; a CVE may affect products outside it.