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Findings

Vulnerability · CVE-2026-78669

Excessive CPU consumption from repeated initial window changes in net/http

Published Oct 8, 2026 · corrected/updated Oct 16, 2026 · evidence confidence high

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.

Grounded briefings

Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.

Executive

CVE-2026-78669 is a unknown public vulnerability record for this product. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.

System administrator

Identify whether this product is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: golang.org/x/net (0 → 0.60.0); stdlib (0 → 1.26.9); stdlib (1.27.0-0 → 1.27.2). Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.

Security analyst

Signals on file: EPSS 0.6%. It is not currently listed in the CISA Known Exploited catalog. Sources contributing to this record: cve_org, epss, go_vulndb. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.

Exploitation and remediation

  • Exploitation evidence

    Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.

  • Patch and remediation

    No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.

  • Safe detection guidance

    Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 8, 2026 · Go Vulnerability Database

    Detected

    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.

  2. Oct 16, 2026 · Go Vulnerability Database

    Fix available

    stdlib fixed in 1.26.9; stdlib fixed in 1.27.2; golang.org/x/net fixed in 0.60.0

  3. Oct 16, 2026 · Go Vulnerability Database

    Fix available

    stdlib fixed in 1.26.9

  4. Oct 16, 2026 · Go Vulnerability Database

    Fix available

    stdlib fixed in 1.27.2

  5. Oct 16, 2026 · Go Vulnerability Database

    Fix available

    golang.org/x/net fixed in 0.60.0

  6. Oct 16, 2026 · Go Vulnerability Database

    Updated

    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.

Affected

  • Go golang.org/x/net0 → 0.60.0
  • Go stdlib0 → 1.26.9
  • Go stdlib1.27.0-0 → 1.27.2

Sources

References