Vulnerability in Fastly H20

CVE-2025-8671

A mismatch caused by client-triggered server-sent stream resets between HTTP/2 specifications and the internal architectures of some HTTP/2 implementations may result in excessive server resource consumption leading to denial-of-service (D…

EPSS: 0.046 (90.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-8671?
CVE-2025-8671 is a high-severity vulnerability in Fastly H20, classified under Improper Resource Shutdown or Release. CVSS score: 7.5/10. Published 2025-08-13.
How severe is CVE-2025-8671?
High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2025-8671 known to be exploited?
10 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.