CVE-2026-56853
Apply ReadHeaderTimeout when doing unencrypted HTTP/2 check in net/http
Description
When a server is configured to support unencrypted HTTP/2, it reads a few bytes from each new connection to see if they contain the HTTP/2 client preface. ReadHeaderTimeout is unexpectedly not being applied when doing this.
INFO
Published Date :
Aug. 13, 2026, 10:17 p.m.
Last Modified :
Aug. 13, 2026, 10:17 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-56853
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Ensure ReadHeaderTimeout is applied to HTTP/2 connections.
- Review and enforce connection timeout settings.
- Disable unencrypted HTTP/2 support if feasible.
- Update server software to the latest version.
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-2026-56853.
| URL | Resource |
|---|---|
| https://go.dev/cl/795540 | |
| https://go.dev/issue/80205 | |
| https://groups.google.com/g/golang-announce/c/94pEornpRlI | |
| https://pkg.go.dev/vuln/GO-2026-6089 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-56853 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-2026-56853
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-2026-56853 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-56853 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.
-
New CVE Received by [email protected]
Aug. 13, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Go standard library', 'product': 'net/http', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '1.25.13', 'versionType': 'semver'}, {'status': 'affected', 'version': '1.26.0-0', 'lessThan': '1.26.6', 'versionType': 'semver'}, {'status': 'affected', 'version': '1.27.0-0', 'lessThan': '1.27.0-rc.3', 'versionType': 'semver'}], 'packageName': 'net/http', 'collectionURL': 'https://pkg.go.dev', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'conn.readRequest'}, {'name': 'conn.serve'}, {'name': 'ListenAndServe'}, {'name': 'ListenAndServeTLS'}, {'name': 'Serve'}, {'name': 'ServeTLS'}, {'name': 'Server.ListenAndServe'}, {'name': 'Server.ListenAndServeTLS'}, {'name': 'Server.Serve'}, {'name': 'Server.ServeTLS'}]}] Added Description When a server is configured to support unencrypted HTTP/2, it reads a few bytes from each new connection to see if they contain the HTTP/2 client preface. ReadHeaderTimeout is unexpectedly not being applied when doing this. Added Reference https://go.dev/cl/795540 Added Reference https://go.dev/issue/80205 Added Reference https://groups.google.com/g/golang-announce/c/94pEornpRlI Added Reference https://pkg.go.dev/vuln/GO-2026-6089