CVE-2026-78659

CVE Enrichment

CVSS: 7.5 HIGH
EPSS: 0.57%
EPSS Percentile: 45.70%
CISA KEV: Not listed

Description

When "Trailer" headers are sent by a client, the HTTP server internally uses the header values to populate the Request.Trailer map passed to the server handler. Because Request.Trailer is a map, each entry incurs memory overhead. For HTTP/2 servers, a malicious client can exploit this by sending a "Trailer" header that declares a large number of fields, causing the server to allocate a disproportionate amount of memory while bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits. This exploit is not applicable for HTTP/1 servers, which do not support multiplexing a large number of requests over one TCP connection, and whose Server.MaxHeaderBytes are calculated differently.

Technical Details

CVSS Version: 3.1
CNA / NVD Source: security@golang.org
Published: 09-Oct-2026 06:17
Last Modified: 09-Oct-2026 23:35
EPSS Date: 2026-10-13
CWE: CWE-405

CVSS Vector


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

References

Last enrichment sync: 14-Oct-2026 21:03
Sources: NVD · FIRST EPSS · CISA KEV
Latest successful provider update; providers refresh independently.

Reported Context (1)

CVE-2026-78659 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.