Vulnerabilities
Misconfiguration
Compliance
CVE Vulnerabilities

CVE-2026-39821

Improper Validation of Unsafe Equivalence in Input

Published: May 22, 2026 | Modified: Jul 10, 2026
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
RedHat/V2
RedHat/V3
8.2 IMPORTANT
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-39821
CWEhttps://cwe.mitre.org/data/definitions/1289.html

The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode(xn–example-.com) incorrectly returns the name example.com rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject example.com but permit xn–example-.com. If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name example.com.

Weakness

The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.

Affected Software

NameVendorStart VersionEnd Version
NetGolang*0.55.0 (excluding)
Red Hat Enterprise Linux 10RedHatgit-lfs-0:3.7.1-5.el10_2.5*
Red Hat Enterprise Linux 10RedHatopentelemetry-collector-0:0.152.1-1.el10_2*
Red Hat Enterprise Linux 10RedHatgrafana-pcp-0:5.3.0-7.el10_2*
Red Hat Enterprise Linux 10RedHatgrafana-0:10.2.6-27.el10_2*
Red Hat Enterprise Linux 10RedHatgolang-0:1.26.5-1.el10_2*
Red Hat Enterprise Linux 8RedHatgit-lfs-0:3.4.1-11.el8_10*
Red Hat Enterprise Linux 8RedHatgrafana-0:9.2.10-31.el8_10*
Red Hat Enterprise Linux 8RedHatgrafana-pcp-0:5.1.1-16.el8_10*
Red Hat Enterprise Linux 9RedHatgit-lfs-0:3.7.1-4.el9_8.1*
Red Hat Enterprise Linux 9RedHatopentelemetry-collector-0:0.152.1-1.el9_8*
Red Hat Enterprise Linux 9RedHatgrafana-0:10.2.6-23.el9_8*
Red Hat Enterprise Linux 9RedHatgrafana-pcp-0:5.1.1-17.el9_8*
Red Hat Enterprise Linux 9RedHatgolang-0:1.26.5-1.el9_8*
Red Hat OpenShift Container Platform 4.22RedHatose-azure-acr-image-credential-provider-0:4.22.0-202606291123.p2.ga17a3e3.assembly.stream.el8*
RHEM 1.0 for RHEL 9RedHatflightctl-0:1.0.3-1.el9em*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/distributed-tracing-console-plugin-pf4-rhel9:1782840519*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/distributed-tracing-console-plugin-pf5-rhel9:1782839981*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/distributed-tracing-console-plugin-pf6-rhel9:1782839193*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/distributed-tracing-console-plugin-rhel9:1782838753*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/logging-console-plugin-pf4-rhel9:1782839279*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/logging-console-plugin-pf5-rhel9:1782840539*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/monitoring-console-plugin-pf5-rhel9:1782844225*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/monitoring-console-plugin-pf6-rhel9:1782839658*
Cluster Observability Operator 1.5.0RedHatcluster-observability-operator/monitoring-console-plugin-rhel9:1782838476*
DevWorkspace Operator 0.42RedHatdevworkspace/devworkspace-rhel9-operator:1782401674*
Logging Subsystem for Red Hat OpenShift 6.4RedHatopenshift-logging/eventrouter-rhel9:1782408807*
Multicluster engine for Kubernetes 2.6RedHatmulticluster-engine/assisted-service-8-rhel8:1783332008*
Multicluster engine for Kubernetes 2.6RedHatmulticluster-engine/assisted-service-9-rhel9:1783333268*
Multicluster engine for Kubernetes 2.8RedHatmulticluster-engine/kube-rbac-proxy-mce-rhel9:1782477094*
Multicluster engine for Kubernetes 2.8RedHatmulticluster-engine/multicloud-manager-rhel9:1782308518*
Multicluster engine for Kubernetes 2.9RedHatmulticluster-engine/discovery-rhel9:1783260894*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/acm-grafana-rhel9:1782383730*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/acm-multicluster-observability-addon-rhel9:1782156698*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/acm-prometheus-config-reloader-rhel9:1782157632*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/acm-prometheus-rhel9:1782157829*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/cluster-backup-rhel9-operator:1782157630*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/endpoint-monitoring-rhel9-operator:1782382580*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/grafana-dashboard-loader-rhel9:1782383255*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/kube-rbac-proxy-rhel9:1782488873*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/kube-state-metrics-rhel9:1782157507*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/metrics-collector-rhel9:1782396604*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/multicluster-observability-rhel9-operator:1782382711*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/node-exporter-rhel9:1782157546*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/observatorium-rhel9:1782157471*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/observatorium-rhel9-operator:1782157018*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/prometheus-alertmanager-rhel9:1782156920*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/prometheus-rhel9:1782374537*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/rbac-query-proxy-rhel9:1782383676*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/thanos-receive-controller-rhel9:1782156860*
Red Hat Advanced Cluster Management for Kubernetes 2.13RedHatrhacm2/thanos-rhel9:1782465412*
Red Hat Advanced Cluster Security for Kubernetes 4.10RedHatadvanced-cluster-security/rhacs-main-rhel8:1781686458*
Red Hat Advanced Cluster Security for Kubernetes 4.11RedHatadvanced-cluster-security/rhacs-main-rhel9:1783352589*
Red Hat Advanced Cluster Security for Kubernetes 4.9RedHatadvanced-cluster-security/rhacs-main-rhel8:1781686446*
Red Hat Edge Manager 1.0RedHatrhem/flightctl-ui-rhel9:1783502438*
Red Hat Enterprise Linux AI 3.4RedHatrhelai3/disk-image-cuda-rhel9:1782804957*
Red Hat Enterprise Linux AI 3.4RedHatrhelai3/bootc-aws-cuda-rhel9:1782758407*
Red Hat Enterprise Linux AI 3.4RedHatrhelai3/bootc-azure-cuda-rhel9:1782758410*
Red Hat Enterprise Linux AI 3.4RedHatrhelai3/bootc-azure-rocm-rhel9:1782754093*
Red Hat Enterprise Linux AI 3.4RedHatrhelai3/bootc-cuda-rhel9:1782744816*
Red Hat Enterprise Linux AI 3.4RedHatrhelai3/bootc-gcp-cuda-rhel9:1782758409*
Red Hat Enterprise Linux AI 3.4RedHatrhelai3/bootc-rocm-rhel9:1782744830*
Red Hat Hardened ImagesRedHatgolang1-25-main-1.25.11-2.hum1*
Red Hat Hardened ImagesRedHatgolang1-26-main-1.26.4-2.hum1*
Red Hat OpenShift Builds 1.7.4RedHatopenshift-builds/openshift-builds-controller-rhel9:1783057515*
Red Hat OpenShift Builds 1.7.4RedHatopenshift-builds/openshift-builds-waiters-rhel9:1783057868*
Red Hat Openshift Data Foundation 4.22RedHatodf4/cephcsi-rhel9:1782932114*
Red Hat Openshift Data Foundation 4.22RedHatodf4/cephcsi-rhel9-operator:1782931768*
Red Hat Openshift Data Foundation 4.22RedHatodf4/devicefinder-rhel9:1782932104*
Red Hat Openshift Data Foundation 4.22RedHatodf4/mcg-core-rhel9:1783536000*
Red Hat Openshift Data Foundation 4.22RedHatodf4/mcg-rhel9-operator:1783535989*
Red Hat Openshift Data Foundation 4.22RedHatodf4/ocs-client-console-rhel9:1783536515*
Red Hat Openshift Data Foundation 4.22RedHatodf4/ocs-client-rhel9-operator:1782932521*
Red Hat Openshift Data Foundation 4.22RedHatodf4/ocs-metrics-exporter-rhel9:1783018461*
Red Hat Openshift Data Foundation 4.22RedHatodf4/ocs-rhel9-operator:1783018421*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-blackbox-exporter-rhel9:1782932812*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-cli-rhel9:1783537001*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-cloudnative-pg-rhel9-operator:1782932919*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-console-rhel9:1783537586*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-cosi-sidecar-rhel9:1782932969*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-csi-addons-rhel9-operator:1782933015*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-csi-addons-sidecar-rhel9:1782933042*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-drbd-rhel9:1783537392*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-external-snapshotter-rhel9-operator:1782933235*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-external-snapshotter-sidecar-rhel9:1782933251*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-multicluster-console-rhel9:1783537955*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-multicluster-rhel9-operator:1782933417*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-must-gather-rhel9:1783537742*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odf-rhel9-operator:1782933602*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odr-rhel9-operator:1783019377*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odr-volsync-plugin-mover-rhel9:1782934054*
Red Hat Openshift Data Foundation 4.22RedHatodf4/odr-volsync-plugin-rhel9-operator:1782934036*
Red Hat Openshift Data Foundation 4.22RedHatodf4/rook-ceph-rhel9-operator:1782934284*
Red Hat OpenShift Dev Spaces 3.29RedHatdevspaces/udi-rhel9:1782991491*
Red Hat OpenShift GitOps 1.19RedHatopenshift-gitops-1/dex-rhel8:1782292352*
Red Hat OpenShift GitOps 1.20RedHatopenshift-gitops-1/dex-rhel9:1782383826*
Red Hat OpenShift Service Mesh 2.6RedHatopenshift-service-mesh/kiali-rhel8:1782287580*
Red Hat OpenShift Service Mesh 3RedHatopenshift-service-mesh/kiali-rhel9:1782201833*
Red Hat OpenShift Service Mesh 3.1RedHatopenshift-service-mesh/kiali-rhel9:1782201537*
Red Hat OpenShift Service Mesh 3.2RedHatopenshift-service-mesh/kiali-rhel9:1782201812*
Red Hat OpenShift Service Mesh 3.3RedHatopenshift-service-mesh/kiali-rhel9:1782201466*
Red Hat Trusted Artifact Signer 1.4RedHatconforma-cli-stack-v1-4-1.4.2*
Red Hat Trusted Artifact Signer 1.4RedHatconforma-cli-stack-v1-4-1.4.2*
Golang-golang-x-net-devUbuntuesm-apps/bionic*
Golang-golang-x-net-devUbuntuesm-apps/focal*

Extended Description

Attackers can sometimes bypass input validation schemes by finding inputs that appear to be safe, but will be dangerous when processed at a lower layer or by a downstream component. For example, a simple XSS protection mechanism might try to validate that an input has no “” tags using case-sensitive matching, but since HTML is case-insensitive when processed by web browsers, an attacker could inject “” and trigger XSS.

Potential Mitigations

  • Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

References

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