CVE-2026-78659
Last modified
CVE-2026-78659 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.23% chance of exploitation in the next 30 days.
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.
Metrics
Weakness Enumeration
Affected Software
Source: CNA advisory (CVE.org). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| Go standard library | net/http | < 1.26.9 |
| Go standard library | net/http/internal/http2 | >= 1.27.0-0, < 1.27.2 |
| golang.org/x/net | golang.org/x/net/http2 | < 0.60.0 |
References
Timeline
- Published
- Last Modified
- Status
- Awaiting Analysis
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