CVE-2019-9517
Synology
- Published
- 13 August 2019
- Last modified
- 17 June 2026
- CVSS
- 7.5 v3.1
- Severity
- high
- EPSS
- 27.9% (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 unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.
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 27.9% 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
Vendor advisory and patch
- https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html
- https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00004.html 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://www.openwall.com/lists/oss-security/2019/08/15/7 third-party
- https://access.redhat.com/errata/RHSA-2019:2893 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-2019:2946 third-party
- https://access.redhat.com/errata/RHSA-2019:2949 third-party
- https://access.redhat.com/errata/RHSA-2019:2950 third-party
- https://access.redhat.com/errata/RHSA-2019:2955 third-party
- https://access.redhat.com/errata/RHSA-2019:3932 third-party
- https://access.redhat.com/errata/RHSA-2019:3933 third-party
- https://access.redhat.com/errata/RHSA-2019:3935 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/4610762456644181b267c846423b3a990bd4aaea1886ecc7d51febdb%40%3Cannounce.httpd.apache.org%3E
- https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/d89f999e26dfb1d50f247ead1fe8538014eb412b2dbe5be4b1a9ef50%40%3Cdev.httpd.apache.org%3E
- https://lists.apache.org/thread.html/ec97fdfc1a859266e56fef084353a34e0a0b08901b3c1aa317a43c8c%40%3Cdev.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r03ee478b3dda3e381fd6189366fa7af97c980d2f602846eef935277d%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r06f0d87ebb6d59ed8379633f36f72f5b1f79cadfda72ede0830b42cf%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r3c5c3104813c1c5508b55564b66546933079250a46ce50eee90b2e36%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/rd2fb621142e7fa187cfe12d7137bf66e7234abcbbcd800074c84a538%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.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/BP556LEG3WENHZI5TAQ6ZEBFTJB4E2IS/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CMNFX5MNYRWWIMO4BTKYQCGUDMHO3AXP/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XHTKU7YQ5EEP2XNSAV4M4VJ7QCBOJMOD/
- https://seclists.org/bugtraq/2019/Aug/47 third-party
- https://security.gentoo.org/glsa/201909-04 third-party
- https://security.netapp.com/advisory/ntap-20190823-0003/ third-party
- https://security.netapp.com/advisory/ntap-20190823-0005/ third-party
- https://security.netapp.com/advisory/ntap-20190905-0003/ third-party
- https://support.f5.com/csp/article/K02591030 third-party
- https://support.f5.com/csp/article/K02591030?utm_source=f5support&%3Butm_medium=RSS
- https://usn.ubuntu.com/4113-1/ third-party
- https://www.debian.org/security/2019/dsa-4509 third-party
- https://www.oracle.com/security-alerts/cpuapr2020.html third-party
- https://www.synology.com/security/advisory/Synology_SA_19_33 third-party
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00004.html 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://www.openwall.com/lists/oss-security/2019/08/15/7 third-party
- https://access.redhat.com/errata/RHSA-2019:2893 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-2019:2946 third-party
- https://access.redhat.com/errata/RHSA-2019:2949 third-party
- https://access.redhat.com/errata/RHSA-2019:2950 third-party
- https://access.redhat.com/errata/RHSA-2019:2955 third-party
- https://access.redhat.com/errata/RHSA-2019:3932 third-party
- https://access.redhat.com/errata/RHSA-2019:3933 third-party
- https://access.redhat.com/errata/RHSA-2019:3935 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/4610762456644181b267c846423b3a990bd4aaea1886ecc7d51febdb%40%3Cannounce.httpd.apache.org%3E
- https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/d89f999e26dfb1d50f247ead1fe8538014eb412b2dbe5be4b1a9ef50%40%3Cdev.httpd.apache.org%3E
- https://lists.apache.org/thread.html/ec97fdfc1a859266e56fef084353a34e0a0b08901b3c1aa317a43c8c%40%3Cdev.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r03ee478b3dda3e381fd6189366fa7af97c980d2f602846eef935277d%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r06f0d87ebb6d59ed8379633f36f72f5b1f79cadfda72ede0830b42cf%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r3c5c3104813c1c5508b55564b66546933079250a46ce50eee90b2e36%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/rd2fb621142e7fa187cfe12d7137bf66e7234abcbbcd800074c84a538%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E
- https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.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/BP556LEG3WENHZI5TAQ6ZEBFTJB4E2IS/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CMNFX5MNYRWWIMO4BTKYQCGUDMHO3AXP/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XHTKU7YQ5EEP2XNSAV4M4VJ7QCBOJMOD/
- https://seclists.org/bugtraq/2019/Aug/47 third-party
- https://security.gentoo.org/glsa/201909-04 third-party
- https://security.netapp.com/advisory/ntap-20190823-0003/ third-party
- https://security.netapp.com/advisory/ntap-20190823-0005/ third-party
- https://security.netapp.com/advisory/ntap-20190905-0003/ third-party
- https://support.f5.com/csp/article/K02591030 third-party
- https://support.f5.com/csp/article/K02591030?utm_source=f5support&%3Butm_medium=RSS
- https://usn.ubuntu.com/4113-1/ third-party
- https://www.debian.org/security/2019/dsa-4509 third-party
- https://www.oracle.com/security-alerts/cpuapr2020.html 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.