CVE-2026-78659
HTTP/2 server memory exhaustion due to Trailer headers in net/http
At a glance
- Source
- NVD
- EPSS
- EPSS 0.63 % · percentile 50 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- Go
- NVD status
- Awaiting Analysis
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.
Weaknesses (CWE)
- CWE-405 — Asymmetric Resource Consumption (Amplification)
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CISA-ADP |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary) |
Advisories
- GO-2026-6603 — HTTP/2 server memory exhaustion due to Trailer headers in net/http
European references
- ENISA EUVD · EUVD-2026-95419
- GCVE · GCVE-0-2026-78659
CERT-FR advisories
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| Go standard library · net/http | affected 0 < 1.26.9 |
| Go standard library · net/http/internal/http2 | affected 1.27.0-0 < 1.27.2 |
| golang.org/x/net · golang.org/x/net/http2 | affected 0 < 0.60.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |