SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2019-9517

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service.

HIGH 7.5EPSS 27.9%

Does this matter?

EPSS puts the probability of exploitation in the next 30 days at 27.9%, higher than 98% of all known CVEs. Patch or mitigate before the next change window.

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.

CVSS 3.1
7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
27.89% probability · 98th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-400, CWE-770
Affected
apple/swiftnio · apache/http server · apache/traffic server · canonical/ubuntu linux · debian/debian linux · synology/skynas · synology/diskstation manager · synology/vs960hd firmware · fedoraproject/fedora · opensuse/leap · redhat/jboss core services · redhat/jboss enterprise application platform · redhat/openshift service mesh · redhat/quay · redhat/software collections · redhat/enterprise linux · oracle/communications element manager · oracle/graalvm · oracle/instantis enterprisetrack · oracle/retail xstore point of service · +3 more
Source
cret@cert.org
EPSS trend
0%15%30%3 November 2026: 27.89%3 November 20263 November 2026

EPSS 27.9% since 3 November 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.