CVE-2026-78669
Description
A flaw was found in the Go net/http package. This flaw allows a remote attacker to cause a Denial of Service (DoS) by triggering excessive CPU consumption on an affected client or server. By opening a large number of HTTP/2 streams and repeatedly sending small configuration (SETTINGS) frames that modify window sizes, an attacker forces the system into intensive state processing. This resource exhaustion degrades performance and can render the service unresponsive.
Statement
A flaw was found in the Go net/http package and the golang.org/x/net/http2 module. A malicious HTTP/2 peer can cause excessive CPU consumption by opening a large number of HTTP/2 streams and then sending many small SETTINGS frames containing SETTINGS_INITIAL_WINDOW_SIZE values. Each SETTINGS frame forces the server or client to iterate over all open streams to adjust their flow-control windows, resulting in quadratic CPU usage and denial of service.
This vulnerability affects all Go programs that serve or consume HTTP/2 traffic using net/http or golang.org/x/net/http2.
Mitigation
In case you consume HTTP2, upgrade to a patched version of the http module.
Verify:
go version
go list -m golang.org/x/net
govulncheck ./...
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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