Go HTTP/2 Server amplification

Summaryinfo

A vulnerability was found in Go and classified as problematic. This affects an unknown part of the component HTTP2 Server. The manipulation results in amplification. This vulnerability is reported as CVE-2026-78659. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as problematic has been found in Go (the affected version is unknown). Affected is an unknown code of the component HTTP2 Server. The manipulation with an unknown input leads to a amplification vulnerability. CWE is classifying the issue as CWE-405. The product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is "asymmetric." This is going to have an impact on availability. CVE summarizes:

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.

This vulnerability is traded as CVE-2026-78659 since 08/25/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-95419). Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• Go

CPE 2.3info

• 🔒

CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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