High [CVE-2026-56853] Go net/http: Unencrypted HTTP/2 connections vulnerable to Denial of Service
This high-severity Red Hat Linux advisory covers CVE-2026-56853 affecting Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
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Summary
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.
A flaw was found in the `net/http` component of the Go standard library. This oversight could allow a remote attacker to maintain open connections indefinitely, potentially leading to a Denial of Service (DoS) by exhausting server resources.
Important: Unencrypted HTTP/2 servers are susceptible to a denial of service due to improper handling of ReadHeaderTimeout during the client preface reading phase. This can lead to resource exhaustion and service unavailability in affected Red Hat products configured to support unencrypted HTTP/2.
Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-770.
Affected products named by the advisory: Red Hat Enterprise Linux 10.0 Extended Update Support; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions; and 52 more.
Affected products named by the advisory: Red Hat Enterprise Linux 9.6 Extended Update Support; Custom Metric Autoscaler 2.19; external secrets operator for Red Hat OpenShift 1.2; Logging Subsystem for Red Hat OpenShift 6.6; and 48 more.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 22 days ago·verify at source
- golang-0:1.26.7-1.el10_2
- go-fdo-server-0:1.0.1-2.el10_2.4
- golang-github-openprinting-ipp-usb-0:0.9.27-7.el10_2.3
- grafana-0:10.2.6-28.el10_2.5
- grafana-pcp-0:5.3.0-8.el10_2.1
- buildah-2:1.43.1-5.el10_2
- buildah-2:1.43.1-6.el10_2
- skopeo-2:1.22.2-5.el10_2
- opentelemetry-collector-0:0.152.1-2.el10_2
- image-builder-0:52.1-1.el10_2.2
- osbuild-composer-0:165.1-3.el10_2.2
- golang-0:1.26.7-1.el10_0
- ignition-0:2.21.0-3.el10_0.4
- delve-0:1.26.1-2.el10_0
- osbuild-composer-0:134.1-12.el10_0
- grafana-pcp-0:5.3.0-1.el10_0.1
- go-toolset:rhel8-8100020260824145918.a3795dee
- grafana-0:9.2.10-33.el8_10
- grafana-pcp-0:5.1.1-18.el8_10
- container-tools:rhel8-8100020260901110702.afee755d
- rhc-1:0.2.5-10.el8_10
- osbuild-composer-0:101.5-2.el8_10
- golang-0:1.26.7-1.el9_8
- grafana-0:10.2.6-23.el9_8.3
- opentelemetry-collector-0:0.152.1-2.el9_8
- osbuild-composer-0:165.1-4.el9_8.1
- image-builder-0:52.1-1.el9_8.2
- golang-0:1.26.7-1.el9_2
- osbuild-composer-0:76.1-9.el9_2
- ignition-0:2.15.0-2.el9_2.1
- golang-0:1.26.7-1.el9_4
- osbuild-composer-0:101.3-4.el9_4.6
- ignition-0:2.17.0-2.el9_4.2
- golang-0:1.26.7-1.el9_6
- osbuild-composer-0:132.2-12.el9_6
- ignition-0:2.21.0-7.el9_6.1
- custom-metrics-autoscaler/custom-metrics-autoscaler-adapter-rhel9:1788361753
- custom-metrics-autoscaler/custom-metrics-autoscaler-admission-webhooks-rhel9:1788361758
- custom-metrics-autoscaler/custom-metrics-autoscaler-http-add-on-interceptor-rhel9:1788290523
- custom-metrics-autoscaler/custom-metrics-autoscaler-http-add-on-operator-rhel9:1788290620
- RHSA-2026:60306
- RHSA-2026:62578
- RHSA-2026:62631
- RHSA-2026:63022
- RHSA-2026:63119
- RHSA-2026:63332
- RHSA-2026:64777
- RHSA-2026:64818
- RHSA-2026:65116
- RHSA-2026:65534
Official advisory · high-confidence parse· fetched 22 days ago·verify at source
Mitigation
Upgrade to a fixed release: golang-0:1.26.7-1.el10_2, go-fdo-server-0:1.0.1-2.el10_2.4, golang-github-openprinting-ipp-usb-0:0.9.27-7.el10_2.3, grafana-0:10.2.6-28.el10_2.5, grafana-pcp-0:5.3.0-8.el10_2.1, buildah-2:1.43.1-5.el10_2. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 22 days ago·verify at source
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