High severity · published Oct 8, 2026
CVE-2026-78669
Excessive CPU consumption from repeated initial window changes in net/http
7.5
CVSS
0.6%
EPSS
No
On KEV
Description
A malicious HTTP/2 peer can cause excessive CPU consumption in the client or server by opening a large number of streams and then sending many small SETTINGS frames containing SETTINGS_INITIAL_WINDOW_SIZE values.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 49% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
GO
golang.org/x/net/http2 · golang.org/x/net
before 0.60.0 · source: vendor
NE
net/http · Go standard library
before 1.26.9 · source: vendor
NE
net/http/internal/http2 · Go standard library
1.27.0-0 before 1.27.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-78669
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-78669
go.dev
https://go.dev/cl/847186
go.dev
https://go.dev/cl/847308
go.dev
https://go.dev/issue/81742
groups.google.com
https://groups.google.com/g/golang-announce/c/U2fTuyDJznI
groups.google.com
https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs
pkg.go.dev
https://pkg.go.dev/vuln/GO-2026-6611
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