CVE-2026-56853
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductStdlib
PublishedAug 13, 2026
First seenAug 13, 2026
Weakness typeCWE-770Allocation of resources without limits
How to fix
Update
- stdlib1.25.13, 1.26.6, 1.27.0-rc.3 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| stdlibGo | v < 1.25.13, 1.26.0-0 ≤ v < 1.26.6, 1.27.0-0 ≤ v < 1.27.0-rc.3 | 1.25.13, 1.26.6, 1.27.0-rc.3 |
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