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.
Published:
2026-10-08
Score:
n/a
EPSS:
n/a
KEV:
No
Analysis and contextual insights are available on OpenCVE Cloud.
Remediation
No solution or workaround provided in the CVE record.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
Sign in to view the affected projects.
Advisories
No advisories yet.
References
History
Thu, 08 Oct 2026 23:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | HTTP/2 server memory exhaustion due to Trailer headers in net/http | |
| References |
|
Subscriptions
No data.
Status: PUBLISHED
Assigner: Go
Published:
Updated: 2026-10-08T22:53:58.192Z
Reserved: 2026-08-24T23:36:03.109Z
Link: CVE-2026-78659
No data.
Status : Received
Published: 2026-10-08T23:17:03.270
Modified: 2026-10-08T23:17:03.270
Link: CVE-2026-78659
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.