7.5
High
CVE-2026-78659 When "Trailer" headers are sent by a client, the HTTP server internally uses the header values to populate the…
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.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| net/http 1.26 | earliest → < 1.26.9 | 1.26.9 |
| net/http/internal/http2 1.27 | 1.27.0-0 → < 1.27.2 | 1.27.2 |
| golang.org/x/net/http2 0.60 | earliest → < 0.60.0 | 0.60.0 |
References
- go.dev go.dev
- go.dev go.dev
- go.dev go.dev
- groups.google.com groups.google.com
- groups.google.com groups.google.com
- pkg.go.dev pkg.go.dev
Timeline
- Published
- Last modified
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