Quadratic complexity in golang.org/x/net HTML text coalescing
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Partial Red Hat: 68 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-407.
Summary
The golang.org/x/net/html package in golang.org/x/net before 0.62.0 concatenates text onto existing text nodes during HTML parsing, copying the accumulated string on every token. Inputs with many short text runs separated by ignored end tags therefore cause quadratic allocations and byte copies (CWE-407). An unauthenticated remote attacker can supply such HTML to a service that parses it.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
When coalescing adjacent text nodes in addText and fosterParent, appending to an existing TextNode's Data via string concatenation (n.Data += text) reallocated and copied the accumulated string on every token. Inputs containing many short text runs separated by ignored end tags (such as "a</x>") caused O(n^2) allocations and byte copies. Accumulate coalesced text in per-node byte slices during parsing and materialize Data strings once at the end of parse.
Why it matters now
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 | golang.org/x/net/html | before 0.62.0 | 0.62.0 | Patch available | CNA |
- golang.org/x/net/html VendorGo standard library Affected before 0.62.0 Fixed in 0.62.0 Patch available CNA
Remediation
Update golang.org/x/net to version 0.62.0, which fixes golang.org/x/net/html. Red Hat lists these products as affected with no fix: AWS Load Balancer Operator, Ansible Automation Orchestrator 2026, Assisted Installer for Red Hat OpenShift Container Platform 2, Builds for Red Hat OpenShift, Compliance Operator, and other products.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA golang.org/x/net/html (golang.org/x/net) Fixed in 0.62.0
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
golang.org/x/net/html 0.62.0
2 records Highest priority Priority LOW 2 LOW
Other records, highest priority first
- TI-2026-81567 Namespace check flaw in golang.org/x/net HTML text renderingPriority LOW 27
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| AWS Load Balancer Operator | Affected | — |
| Ansible Automation Orchestrator 2026 | Affected | — |
| Assisted Installer for Red Hat OpenShift Container Platform 2 | Affected | — |
| Builds for Red Hat OpenShift | Affected | — |
| Compliance Operator | Affected | — |
| Confidential Compute Attestation | Affected | — |
| Cost Management On Premise | Affected | — |
| Cryostat 4 | Affected | — |
| Fence Agents Remediation Operator | Affected | — |
| File Integrity Operator | Affected | — |
| Gatekeeper 3 | Affected | — |
| Logging Subsystem for Red Hat OpenShift | Affected | — |
| Logical Volume Manager Storage | Affected | — |
| Migration Toolkit for Applications 8 | Affected | — |
| Migration Toolkit for Containers | Affected | — |
| Multiarch Tuning Operator | Affected | — |
| Multicluster Engine for Kubernetes | Affected | — |
| Multicluster Global Hub | Affected | — |
| Multicluster Global Hub 5 | Affected | — |
| Network Observability Operator | Affected | — |
| Node HealthCheck Operator | Affected | — |
| Node Maintenance Operator | Affected | — |
| OpenShift API for Data Protection | Affected | — |
| OpenShift Developer Tools and Services | Affected | — |
| OpenShift Lightspeed | Affected | — |
| OpenShift Serverless | Affected | — |
| OpenShift Service Mesh 3 | Affected | — |
| Red Hat 3scale API Management Platform 2 | Affected | — |
| Red Hat Advanced Cluster Management for Kubernetes 2 | Affected | — |
| Red Hat Advanced Cluster Security 4 | Affected | — |
| Red Hat Ansible Automation Platform 2 | Affected | — |
| Red Hat Ceph Storage 5 | Affected | — |
| Red Hat Ceph Storage 7 | Affected | — |
| Red Hat Ceph Storage 8 | Affected | — |
| Red Hat Ceph Storage 9 | Affected | — |
| Red Hat Certification Program for Red Hat Enterprise Linux 9 | Affected | — |
| Red Hat Connectivity Link 1 | Affected | — |
| Red Hat Developer Hub 1 | Affected | — |
| Red Hat Edge Manager 1 | Affected | — |
| Red Hat Enterprise Linux 10 | Affected | — |
| Red Hat Enterprise Linux 8 | Affected | — |
| Red Hat Enterprise Linux 9 | Affected | — |
| Red Hat Lightspeed for Runtimes Operator | Affected | — |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
| Red Hat OpenShift Cluster Manager CLI | Affected | — |
| Red Hat OpenShift Container Platform 4 | Affected | — |
| Red Hat OpenShift Container Platform 5 | Affected | — |
| Red Hat OpenShift Dev Spaces | Affected | — |
| Red Hat OpenShift Dev Workspaces Operator | Affected | — |
| Red Hat OpenShift GitOps | Affected | — |
| Red Hat OpenShift Virtualization 4 | Affected | — |
| Red Hat OpenShift Virtualization 5 | Affected | — |
| Red Hat OpenShift distributed tracing 3 | Affected | — |
| Red Hat OpenShift for Windows Containers | Affected | — |
| Red Hat OpenShift on AWS | Affected | — |
| Red Hat OpenStack Platform 16.2 | Affected | — |
| Red Hat OpenStack Platform 17.1 | Affected | — |
| Red Hat OpenStack Platform 18.0 | Affected | — |
| Red Hat Openshift Data Foundation 4 | Affected | — |
| Red Hat Quay 3 | Affected | — |
| Red Hat Satellite 6 | Affected | — |
| Red Hat Service Interconnect 2 | Affected | — |
| Red Hat Trusted Artifact Signer | Affected | — |
| Red Hat Web Terminal | Affected | — |
| Security Profiles Operator | Affected | — |
| Zero Trust Workload Identity Manager | Affected | — |
| Zero Trust Workload Identity Manager - Tech Preview | Affected | — |
| cert-manager Operator for Red Hat OpenShift | Affected | — |
Timeline
- 2026-10-27 Threatist record created from CVE-2026-78661
- 2026-10-28 Alias added: GHSA-75pg-wvh3-34jr
- 2026-11-04 CVSS score added · CISA ADP
- 2026-11-04 Weakness changed · CISA ADP
- 2026-11-04 CISA SSVC decision points changed
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CVSS score added · 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-2026-78661 · CVE Program
- CVE-2026-78661 · NVD
- FIRST EPSS
- GHSA-75pg-wvh3-34jr · GitHub Advisory Database · CC BY 4.0
- CVE-2026-78661 · 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