CVE-2026-78660
HTTP/2 transport accepts malformed framing-related headers in net/http
Description
Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling.
INFO
Published Date :
Oct. 8, 2026, 11:17 p.m.
Last Modified :
Oct. 8, 2026, 11:17 p.m.
Remotely Exploit :
No
Source :
[email protected]
Solution
- Ensure strict header validation in HTTP/2.
- Validate headers forwarded to HTTP/1 clients.
- Update affected proxy software.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-78660.
| URL | Resource |
|---|---|
| https://go.dev/cl/835145 | |
| https://go.dev/cl/836385 | |
| https://go.dev/issue/81115 | |
| https://groups.google.com/g/golang-announce/c/U2fTuyDJznI | |
| https://pkg.go.dev/vuln/GO-2026-6610 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-78660 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-78660
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-78660 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-78660 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Oct. 08, 2026
Action Type Old Value New Value Added Description Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/78xxx/CVE-2026-78660.json">CVE-2026-78660</a> Added Reference https://go.dev/cl/835145 Added Reference https://go.dev/cl/836385 Added Reference https://go.dev/issue/81115 Added Reference https://groups.google.com/g/golang-announce/c/U2fTuyDJznI Added Reference https://pkg.go.dev/vuln/GO-2026-6610