CRITICAL 10.0 Microsoft
CVE-2026-39821
Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna
Microsoft Security Update 2026-May: Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna
Affected Products
- azl3 application-gateway-kubernetes-ingress 1.7.7-3 on Azure Linux 3.0
- azl3 azcopy 10.25.1-4 on Azure Linux 3.0
- azl3 azurelinux-image-tools 1.2.0-2 on Azure Linux 3.0
- azl3 cert-manager 1.12.15-6 on Azure Linux 3.0
- azl3 cf-cli 8.7.11-5 on Azure Linux 3.0
- azl3 cloud-provider-kubevirt 0.5.1-3 on Azure Linux 3.0
- azl3 containerd2 2.1.6-2 on Azure Linux 3.0
- azl3 containerized-data-importer 1.62.0-3 on Azure Linux 3.0
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-39821
- https://nvd.nist.gov/vuln/detail/CVE-2026-39821
This critical severity vulnerability with a CVSS score of 10.0 was published on 2026-05-12 via Microsoft. Affected: azl3 application-gateway-kubernetes-ingress 1.7.7-3 on Azure Linux 3.0, azl3 azcopy 10.25.1-4 on Azure Linux 3.0, azl3 azurelinux-image-tools 1.2.0-2 on Azure Linux 3.0 and 5 more.
Risk Timeline
CVE Disclosed2026-05-12 · 173 days ago
Remediation Resources
Official Advisory
msrc.microsoft.com/update-guide/vulnerability/CVE-2026-39821NVD / MITRE
nvd.nist.gov/vuln/detail/CVE-2026-39821Related Vulnerabilities
| CVE | Title | Severity | CVSS |
|---|---|---|---|
| CVE-2026-110264 | Integer Overflow or Wraparound in GitLab | CRITICAL | 10.0 |
| CVE-2026-94603 | Podman: The `podman run` command can be instructed to disable almost all sandbox | CRITICAL | 10.0 |
| CVE-2026-42960 | Possible cache poisoning via promiscuous records for the authority section | CRITICAL | 10.0 |
| CVE-2026-46595 | Invoking VerifiedPublicKeyCallback permissions skip enforcement in golang.org/x | CRITICAL | 10.0 |
| CVE-2025-32433 PoC | Erlang/OTP SSH Vulnerable to Pre-Authentication RCE | CRITICAL | 10.0 |
| CVE-2026-115889 | Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompil | CRITICAL | 9.9 |
vulnfeed aggregates 17991 vulnerabilities from NVD, CISA KEV,
Ubuntu, Debian, Red Hat, Kubernetes, Exploit-DB, OSS-Security, GitHub and OpenStack — updated every 4 hours.