CVE-2026-78663

CVE Enrichment

CVSS: 9.1 CRITICAL
EPSS: 0.57%
EPSS Percentile: 45.89%
CISA KEV: Not listed

Description

The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler reads the buffered data. A malicious client can exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.

Technical Details

CVSS Version: 3.1
CNA / NVD Source: security@golang.org
Published: 09-Oct-2026 06:17
Last Modified: 10-Oct-2026 00:16
EPSS Date: 2026-10-13
CWE: CWE-675

CVSS Vector


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

References

Last enrichment sync: 14-Oct-2026 21:06
Sources: NVD · FIRST EPSS · CISA KEV
Latest successful provider update; providers refresh independently.

Reported Context (1)

CVE-2026-78663 Microsoft October 2026 Updates Fix 1,411 Flaws, Including Three Zero-Days

CVE (1235)

People (2)

MITRE ATT&CK (1)

Vendors (14)

Products (87)

Tools (1)

Note: Related entities, including threat actors, malware, CVEs, MITRE ATT&CK techniques, vendors, products, tools, countries, and industries, are shown when they appear in the same reporting. Their presence does not necessarily mean they were targeted, compromised, vulnerable, responsible for the activity, or directly involved in the incident.