CVE-2019-9515

CVE-2019-9515 is a high-severity vulnerability in Apple Swiftnio with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 88% places it in the 100th 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 a settings flood, potentially leading to a denial of service. The attacker sends a stream of SETTINGS frames to the peer. Since the RFC requires that the peer reply with one acknowledgement per SETTINGS frame, an empty SETTINGS frame is almost equivalent in behavior to a ping. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.

Frequently asked questions

What is CVE-2019-9515?
Some HTTP/2 implementations are vulnerable to a settings flood, potentially leading to a denial of service. The attacker sends a stream of SETTINGS frames to the peer. Since the RFC requires that the peer reply with one acknowledgement per SETTINGS frame, an empty SETTINGS frame is almost equivalent in behavior to a ping. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both.
How severe is CVE-2019-9515?
CVE-2019-9515 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-2019-9515 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 88% (100th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-9515?
CVE-2019-9515 primarily affects Apple Swiftnio. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-9515?
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-2019-9515 published?
CVE-2019-9515 was published on 2019-08-13 and last updated on 2026-06-17.

References

Affected products (29)

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