Memory exhaustion in Go net/http HTTP/2 server via Trailer headers
Priority MEDIUM 40CWE-405Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 13 fixed, 85 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat.
Summary
Go net/http before 1.26.9, net/http/internal/http2 from 1.27.0-0 before 1.27.2, and golang.org/x/net/http2 before 0.60.0 are affected. A client's Trailer header makes an HTTP/2 server allocate memory disproportionately, because each entry in the Request.Trailer map adds overhead and bypasses the header count and size limits (CWE-405). A remote client can send a Trailer header declaring many fields to exhaust server memory. This does not apply to HTTP/1 servers.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
When "Trailer" headers are sent by a client, the HTTP server internally uses the header values to populate the Request.Trailer map passed to the server handler. Because Request.Trailer is a map, each entry incurs memory overhead. For HTTP/2 servers, a malicious client can exploit this by sending a "Trailer" header that declares a large number of fields, causing the server to allocate a disproportionate amount of memory while bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits. This exploit is not applicable for HTTP/1 servers, which do not support multiplexing a large number of requests over one TCP connection, and whose Server.MaxHeaderBytes are calculated differently.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00866 58th percentileScored 2026-11-07
Fix Partial net/http (Go standard library): 1.26.9net/http/internal/http2 (Go standard library): 1.27.2+1 more productRed Hat: 10 advisoriesRed Hat: 13 fixed, 85 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Go standard library | net/http | before 1.26.9 | 1.26.9 | Patch available | CNA |
| Go standard library | net/http/internal/http2 | 1.27.0-0 to before 1.27.2 | 1.27.2 | Patch available | CNA |
| Go standard library | golang.org/x/net/http2 | before 0.60.0 | 0.60.0 | Patch available | CNA |
- net/http VendorGo standard library Affected before 1.26.9 Fixed in 1.26.9 Patch available CNA
- net/http/internal/http2 VendorGo standard library Affected 1.27.0-0 to before 1.27.2 Fixed in 1.27.2 Patch available CNA
- golang.org/x/net/http2 VendorGo standard library Affected before 0.60.0 Fixed in 0.60.0 Patch available CNA
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:golang:go:*:*:*:*:*:*:*:* | — | — | Go standard library |
- cpe:2.3:a:golang:go:*:*:*:*:*:*:*:* Versions — — ·Go standard library
Remediation
Upgrade Go net/http to 1.26.9, net/http/internal/http2 to 1.27.2, and golang.org/x/net/http2 to 0.60.0. Red Hat fixes this in RHSA-2026:86093, RHSA-2026:86196, RHSA-2026:86203, RHSA-2026:87040, RHSA-2026:87041, RHSA-2026:87042, RHSA-2026:87043, RHSA-2026:87245, RHSA-2026:87246, and RHSA-2026:90994. The sources list no fixed version for AWS Load Balancer Operator, Compliance Operator, and other products.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA net/http (Go standard library) Fixed in 1.26.9
- Fix · CNA net/http/internal/http2 (Go standard library) Fixed in 1.27.2
- Fix · CNA golang.org/x/net/http2 (golang.org/x/net) Fixed in 0.60.0
Red Hat 10 advisories
- RHSA-2026:90994 Released 2026-10-27 · Red Hat rating Importantgo-toolset:rhel8 security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream AUS (v.8.4) delve-1.26.1-1.module+el8.4.0+25181+7ce5b91c.src::go-toolset:rhel8, delve-1.26.1-1.module+el8.4.0+25181+7ce5b91c.x86_64::go-toolset:rhel8, go-toolset-1.26.10-2.module+el8.4.0+25201+9a419e96.x86_64::go-toolset:rhel8 +8
- Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) delve-1.26.1-1.module+el8.4.0+25181+7ce5b91c.src::go-toolset:rhel8, delve-1.26.1-1.module+el8.4.0+25181+7ce5b91c.x86_64::go-toolset:rhel8, go-toolset-1.26.10-2.module+el8.4.0+25201+9a419e96.x86_64::go-toolset:rhel8 +8
- RHSA-2026:87245 Released 2026-10-21 · Red Hat rating Importantgo-toolset:rhel8 security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream E4S (v.8.8) delve-1.26.1-1.module+el8.8.0+24781+86ad105d.ppc64le::go-toolset:rhel8, delve-1.26.1-1.module+el8.8.0+24781+86ad105d.src::go-toolset:rhel8, delve-1.26.1-1.module+el8.8.0+24781+86ad105d.x86_64::go-toolset:rhel8 +13
- Red Hat Enterprise Linux AppStream TUS (v.8.8) delve-1.26.1-1.module+el8.8.0+24781+86ad105d.src::go-toolset:rhel8, delve-1.26.1-1.module+el8.8.0+24781+86ad105d.x86_64::go-toolset:rhel8, go-toolset-1.26.10-4.module+el8.8.0+25113+a148ecc0.x86_64::go-toolset:rhel8 +8
- RHSA-2026:87246 Released 2026-10-21 · Red Hat rating Importantgo-toolset:rhel8 security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream AUS (v.8.6) delve-1.26.1-1.module+el8.6.0+24782+a062e766.src::go-toolset:rhel8, delve-1.26.1-1.module+el8.6.0+24782+a062e766.x86_64::go-toolset:rhel8, go-toolset-1.26.10-4.module+el8.6.0+25114+90ecdb41.x86_64::go-toolset:rhel8 +8
- Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) delve-1.26.1-1.module+el8.6.0+24782+a062e766.src::go-toolset:rhel8, delve-1.26.1-1.module+el8.6.0+24782+a062e766.x86_64::go-toolset:rhel8, go-toolset-1.26.10-4.module+el8.6.0+25114+90ecdb41.x86_64::go-toolset:rhel8 +8
Show 7 more Red Hat advisories
- RHSA-2026:87043 Released 2026-10-21 · Red Hat rating Importantgolang security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream EUS (v.9.6) go-toolset-1.26.10-1.el9_6, golang-1.26.10-1.el9_6, golang-bin-1.26.10-1.el9_6 +5
- RHSA-2026:87042 Released 2026-10-21 · Red Hat rating Importantgolang security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream E4S (v.9.4) go-toolset-1.26.10-1.el9_4, golang-1.26.10-1.el9_4, golang-bin-1.26.10-1.el9_4 +5
- RHSA-2026:87041 Released 2026-10-21 · Red Hat rating Importantgolang security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream E4S (v.9.2) go-toolset-1.26.10-1.el9_2, golang-1.26.10-1.el9_2, golang-bin-1.26.10-1.el9_2 +5
- RHSA-2026:87040 Released 2026-10-21 · Red Hat rating Importantgolang security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream EUS (v. 10.0) go-toolset-1.26.10-1.el10_0, golang-1.26.10-1.el10_0, golang-bin-1.26.10-1.el10_0 +5
- RHSA-2026:86196 Released 2026-10-20 · Red Hat rating Importantgolang security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 9) go-toolset-1.26.10-1.el9_8, golang-1.26.10-1.el9_8, golang-bin-1.26.10-1.el9_8 +5
- RHSA-2026:86203 Released 2026-10-20 · Red Hat rating Importantgo-toolset:rhel8 security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 8) delve-1.26.1-1.module+el8.10.0+24516+40554724.aarch64::go-toolset:rhel8, delve-1.26.1-1.module+el8.10.0+24516+40554724.ppc64le::go-toolset:rhel8, delve-1.26.1-1.module+el8.10.0+24516+40554724.src::go-toolset:rhel8 +22
- RHSA-2026:86093 Released 2026-10-20 · Red Hat rating Importantgolang security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 10) go-toolset-1.26.10-1.el10_2, golang-1.26.10-1.el10_2, golang-bin-1.26.10-1.el10_2 +5
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
golang.org/x/net/http2 0.60.0
5 records Highest priority Priority MEDIUM 5 MEDIUM
Other records, highest priority first
- TI-2026-69826 Double flow control refund on HTTP/2 server streams in net/httpPriority MEDIUM 49
- TI-2026-69841 Race condition in Go net/http HPACK encoder crashes HTTP/2 serversPriority MEDIUM 40
- TI-2026-69828 Excessive CPU use from repeated window changes in Go net/httpPriority MEDIUM 40
- Release ·
Go standard library net/http, net/http/internal/http2 1.26.9, 1.27.2
5 records Highest priority Priority MEDIUM 5 MEDIUM
Other records, highest priority first
- TI-2026-69826 Double flow control refund on HTTP/2 server streams in net/httpPriority MEDIUM 49
- TI-2026-69841 Race condition in Go net/http HPACK encoder crashes HTTP/2 serversPriority MEDIUM 40
- TI-2026-69828 Excessive CPU use from repeated window changes in Go net/httpPriority MEDIUM 40
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| AWS Load Balancer Operator | Affected | No fix yet |
| Ansible Automation Orchestrator 2026 | Affected | No fix yet |
| Assisted Installer for Red Hat OpenShift Container Platform 2 | Affected | No fix yet |
| Compliance Operator | Affected | No fix yet |
| Confidential Compute Attestation | Affected | No fix yet |
| Cost Management Metrics Operator | Affected | No fix yet |
| Cost Management On Premise | Affected | No fix yet |
| Cryostat 4 | Affected | No fix yet |
| Custom Metric Autoscaler operator for Red Hat Openshift | Affected | No fix yet |
| DPU kit for NVIDIA | Affected | No fix yet |
| Deployment Validation Operator | Affected | No fix yet |
| Exploit Intelligence | Affected | No fix yet |
| External Secrets Operator for Red Hat OpenShift | Affected | No fix yet |
| Fence Agents Remediation Operator | Affected | No fix yet |
| File Integrity Operator | Affected | No fix yet |
| Gatekeeper 3 | Affected | No fix yet |
| Helm CLI for Red Hat OpenShift | Affected | No fix yet |
| Logging Subsystem for Red Hat OpenShift | Affected | No fix yet |
| Logical Volume Manager Storage | Affected | No fix yet |
| Machine Deletion Remediation Operator | Affected | No fix yet |
| Migration Toolkit for Applications 8 | Affected | No fix yet |
| Migration Toolkit for Containers | Affected | No fix yet |
| Multiarch Tuning Operator | Affected | No fix yet |
| Multicluster Engine for Kubernetes | Affected | No fix yet |
| Multicluster Global Hub | Affected | No fix yet |
| Network Observability Operator | Affected | No fix yet |
| Node HealthCheck Operator | Affected | No fix yet |
| Node Maintenance Operator | Affected | No fix yet |
| Nvidia GPU Driver for RHEL on Openshift | Affected | No fix yet |
| OpenShift API for Data Protection | Affected | No fix yet |
| OpenShift Developer Tools and Services | Affected | No fix planned: Out of support scope |
| OpenShift Lightspeed | Affected | No fix yet |
| OpenShift Pipelines | Affected | No fix yet |
| OpenShift Serverless | Affected | No fix yet |
| OpenShift Service Mesh 3 | Affected | No fix yet |
| OpenShift Source-to-Image (S2I) | Affected | No fix yet |
| Red Hat 3scale API Management Platform 2 | Affected | No fix yet |
| Red Hat Advanced Cluster Management for Kubernetes 2 | Affected | No fix yet |
| Red Hat Advanced Cluster Security 4 | Affected | No fix yet |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet |
| Red Hat Ceph Storage 5 | Affected | No fix yet |
| Red Hat Ceph Storage 6 | Affected | No fix yet |
| Red Hat Ceph Storage 7 | Affected | No fix yet |
| Red Hat Ceph Storage 8 | Affected | No fix yet |
| Red Hat Ceph Storage 9 | Affected | No fix yet |
| Red Hat Certification Program for Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat Connectivity Link 1 | Affected | No fix yet |
| Red Hat Developer Hub 1 | Affected | No fix yet |
| Red Hat Edge Manager 1 | Affected | No fix yet |
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 7 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet |
| Red Hat Hardened Images | Affected | No fix planned: Will not fix |
| Red Hat Lightspeed for Runtimes Operator | Affected | No fix yet |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
| Red Hat OpenShift Cluster Manager CLI | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet |
| Red Hat OpenShift Dev Workspaces Operator | Affected | No fix yet |
| Red Hat OpenShift GitOps | Affected | No fix yet |
| Red Hat OpenShift Virtualization 4 | Affected | No fix yet |
| Red Hat OpenShift distributed tracing 3 | Affected | No fix yet |
| Red Hat OpenShift for Windows Containers | Affected | No fix yet |
| Red Hat OpenShift on AWS | Affected | No fix yet |
| Red Hat OpenStack Platform 16.2 | Affected | No fix yet |
| Red Hat OpenStack Platform 17.1 | Affected | No fix yet |
| Red Hat OpenStack Platform 18.0 | Affected | No fix yet |
| Red Hat Openshift Data Foundation 4 | Affected | No fix yet |
| Red Hat Quay 3 | Affected | No fix yet |
| Red Hat Satellite 6 | Affected | No fix yet |
| Red Hat Service Interconnect 1 | Affected | No fix planned: Out of support scope |
| Red Hat Service Interconnect 2 | Affected | No fix yet |
| Red Hat Trusted Artifact Signer | Affected | No fix yet |
| Red Hat Web Terminal | Affected | No fix yet |
| Secrets Management Console for Red Hat OpenShift | Affected | No fix yet |
| Security Profiles Operator | Affected | No fix yet |
| Self-service automation portal 2 | Affected | No fix yet |
| Zero Trust Workload Identity Manager | Affected | No fix yet |
| Zero Trust Workload Identity Manager - Tech Preview | Affected | No fix yet |
| cert-manager Operator for Red Hat OpenShift | Affected | No fix yet |
| streams for Apache Kafka 2 | Affected | No fix planned: Out of support scope |
| streams for Apache Kafka 3 | Affected | No fix yet |
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2026:86093 |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2026:86203 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2026:86196 |
| Red Hat Enterprise Linux AppStream AUS (v.8.4) | Fixed | RHSA-2026:90994 |
| Red Hat Enterprise Linux AppStream AUS (v.8.6) | Fixed | RHSA-2026:87246 |
| Red Hat Enterprise Linux AppStream E4S (v.8.8) | Fixed | RHSA-2026:87245 |
| Red Hat Enterprise Linux AppStream E4S (v.9.2) | Fixed | RHSA-2026:87041 |
| Red Hat Enterprise Linux AppStream E4S (v.9.4) | Fixed | RHSA-2026:87042 |
| Red Hat Enterprise Linux AppStream EUS (v. 10.0) | Fixed | RHSA-2026:87040 |
| Red Hat Enterprise Linux AppStream EUS (v.9.6) | Fixed | RHSA-2026:87043 |
| Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) | Fixed | RHSA-2026:90994 |
| Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) | Fixed | RHSA-2026:87246 |
| Red Hat Enterprise Linux AppStream TUS (v.8.8) | Fixed | RHSA-2026:87245 |
Not affected: 16 products
- Builds for Red Hat OpenShift
- OpenShift API for Data Protection
- OpenShift Lightspeed
- OpenShift Pipelines
- OpenShift Service Mesh 3
- Red Hat Ceph Storage 7
- Red Hat Ceph Storage 8
- Red Hat Ceph Storage 9
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat Hardened Images
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
- Service Telemetry Framework 1.5
Timeline
- 2026-10-09 Threatist record created from CVE-2026-78659
- 2026-10-10 CVSS score added · CISA ADP
- 2026-10-10 Weakness changed · CISA ADP
- 2026-10-10 CISA SSVC decision points changed
- 2026-10-11 Priority changed: LOW → MEDIUM
- 2026-10-23 Fix available: RHSA-2026:87246 · Red Hat
- 2026-10-23 Fix available: RHSA-2026:86093 · Red Hat
- 2026-10-23 Fix available: RHSA-2026:86196 · Red Hat
- 2026-10-23 Fix available: RHSA-2026:86203 · Red Hat
- 2026-10-23 Fix available: RHSA-2026:87042 · Red Hat
- 2026-10-23 Fix available: RHSA-2026:87040 · Red Hat
- 2026-10-23 Fix available: RHSA-2026:87041 · Red Hat
- 2026-10-23 Fix available: RHSA-2026:87043 · Red Hat
- 2026-10-23 Fix available: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux AppStream (v. 9) +6 · Red Hat
- 2026-10-23 CVSS score added · Red Hat
- 2026-10-24 Fix available: RHSA-2026:87245 · Red Hat
- 2026-10-24 Fix available: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8) · Red Hat
- 2026-10-29 Fix available: RHSA-2026:90994 · Red Hat
- 2026-10-29 Fix available: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) · Red Hat
- 2026-10-30 EPSS moved to the 50th–90th percentile
- 2026-10-30 Affected versions changed · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
- 2026-11-02 Affected versions changed · Red Hat
- 2026-11-02 Affected versions changed · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
More Go standard library vulnerabilities
- TI-2020-00578 Improper certificate validation in Microsoft Windows KEVCVSS 3.1HIGH 8.1
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2023-24278 HTTP/2 CONTINUATION flood in net/http CVSS 3.1HIGH 7.5
- TI-2018-05208 The "go get" implementation in Go 1.9.4, when the -insecure command-line option is used… CVSS 3.1HIGH 8.8
- TI-2024-16309 Panic when parsing invalid palette-color images in golang.org/x/image CVSS 3.1HIGH 7.5
- TI-2022-20112 Request smuggling due to improper request handling in golang.org/x/net/http2/h2c CVSS 3.1HIGH 7.5
Sources
- CVE-2026-78659 · CVE Program
- CVE-2026-78659 · NVD
- FIRST EPSS
- CVE-2026-78659 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences