#VU20340 Resource management error - CVE-2019-9517

Vulnerability identifier: #VU20340

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-9517

CWE-ID: CWE-399

Exploitation vector: Network

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to incorrect implementation of HTTP/2 protocol. A remote attacker can  open 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.

Mitigation
Install updates from vendor's website.

External links
https://www.openwall.com/lists/oss-security/2019/08/15/7
https://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-002.md
https://kb.cert.org/vuls/id/605641/
https://lists.apache.org/thread.html/4610762456644181b267c846423b3a990bd4aaea1886ecc7d51febdb@%3Cannounce.httpd.apache.org%3E
https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba@%3Ccvs.httpd.apache.org%3E
https://lists.apache.org/thread.html/d89f999e26dfb1d50f247ead1fe8538014eb412b2dbe5be4b1a9ef50@%3Cdev.httpd.apache.org%3E
https://lists.apache.org/thread.html/ec97fdfc1a859266e56fef084353a34e0a0b08901b3c1aa317a43c8c@%3Cdev.httpd.apache.org%3E
https://support.f5.com/csp/article/K02591030
https://www.synology.com/security/advisory/Synology_SA_19_33

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.