Vulnerability in golang-golang-x-net-dev (UBUNTU-CVE-2026-39821)
Summary
Vulnerability in golang-golang-x-net-dev (UBUNTU-CVE-2026-39821). Confidential information can be exposed externally. Mitigation: upgrade to 1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3 or later.
Original description
The description as published by the source.
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".
Source: OSV.dev (Open Source Vulnerabilities) OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as UBUNTU-CVE-2026-39821 has been found in golang-golang-x-net-dev.
Confidential information can be exposed externally.
What to do: upgrade golang-golang-x-net-dev to 1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3 or later.
If unsure, ask your IT team or search "golang-golang-x-net-dev UBUNTU-CVE-2026-39821" on the vendor's site.
UBUNTU-CVE-2026-39821 (golang-golang-x-net-dev)
Attack vector: remote (network-reachable) / no user interaction
Patched: 1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in golang-golang-x-net-dev.
Check the vendor advisory for the affected versions of golang-golang-x-net-dev.
Severity: ?. Confidential information can be exposed externally.
Update to 1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'golang-golang-x-net-dev' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'golang-golang-x-net-dev' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
golang-golang-x-net-devを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade golang-golang-x-net-dev to 1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3ステージング環境で 1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory ubuntu.com
- advisory ubuntu.com
- advisory ubuntu.com
- advisory ubuntu.com
- advisory ubuntu.com
- report ubuntu.com
- report cve.org
- report groups.google.com
- report github.com
- report go.dev
- report go.dev
- report pkg.go.dev