CVE-2019-9517

Swiftnio vulnerability

CVSS

7.5

EPSS

27.0%

EPSS pct

98th

Exploited

No known

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.

Affected vendor

Apple

Affected product

Swiftnio

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness type (CWE)

CWE-400 — Uncontrolled Resource Consumption
CWE-770 — Allocation of Resources Without Limits or Throttling

Published

2019-08-13

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to availability.

Its EPSS score of 27.0% reflects a moderate probability of exploitation activity in the wild over the next 30 days, placing it above 98% of all scored CVEs.

Check your external exposure to CVE-2019-9517

Confirm whether Apple Swiftnio is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2019-9517.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2019-9517

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2019-9517 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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