CVE-2019-9511

CVE-2019-9511 is a high-severity vulnerability in Apple Swiftnio with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 58% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-770.

Key facts

Description

Some HTTP/2 implementations are vulnerable to window size manipulation and stream prioritization manipulation, potentially leading to a denial of service. The attacker requests a large amount of data from a specified resource over multiple streams. They manipulate window size and stream priority to force the server to queue the data in 1-byte chunks. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.

Frequently asked questions

What is CVE-2019-9511?
Some HTTP/2 implementations are vulnerable to window size manipulation and stream prioritization manipulation, potentially leading to a denial of service. The attacker requests a large amount of data from a specified resource over multiple streams. They manipulate window size and stream priority to force the server to queue the data in 1-byte chunks. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.
How severe is CVE-2019-9511?
CVE-2019-9511 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2019-9511 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 58% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-9511?
CVE-2019-9511 primarily affects Apple Swiftnio. In total, 28 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-9511?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-9511 published?
CVE-2019-9511 was published on 2019-08-13 and last updated on 2026-06-17.

References

Affected products (28)

More vulnerabilities in Apple Swiftnio

All CVEs affecting Apple Swiftnio →

Other CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities

Browse all CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE: