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CVE-2026-55427
high
CVSS 8.3
Vulnerability in github.com/coder/coder/v2 (CVE-2026-55427)
Summary
vulnerability in github.com/coder/coder/v2 (CVE-2026-55427). Successful exploitation can lead to full system takeover. Exploitable via ``HostnameSuffix``. Mitigation: upgrade to `2.29.17` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-55427** has been found in github.com/coder/coder/v2.
Attackers can target a specific entry point like ``HostnameSuffix`` over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.3/10.
What to do: upgrade github.com/coder/coder/v2 to **2.29.17** or later.
If unsure, ask your IT team or search "github.com/coder/coder/v2 CVE-2026-55427" on the vendor's site.
CVE-2026-55427 (github.com/coder/coder/v2) — CWE-74 / CVSS v3 8.3
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: `HostnameSuffix` / `SSHConfigOptions` / `ProxyCommand`
Patched: `2.29.17` — apply immediately
Workaround: Inspect `coder config-ssh --dry-run` output before applying changes.
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.
❓ What is the problem
**A vulnerability** (CWE-74) exists in github.com/coder/coder/v2. Attackers reach the vulnerable code path via ``HostnameSuffix`` without authentication.
📍 Affected scope
github.com/coder/coder/v2 — . Attack surface: `HostnameSuffix` / `SSHConfigOptions` / `ProxyCommand`.
🔥 Severity
Severity: High (CVSS 8.3/10). Successful exploitation can lead to full system takeover
🔧 How to fix
Update to **2.29.17**.
🛡️ Workaround
Workaround: Inspect `coder config-ssh --dry-run` output before applying changes.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'github.com/coder/coder/v2' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'github.com/coder/coder/v2' . | 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 `github.com/coder/coder/v2` を grep し、稼働しているサービス・バージョンを把握する。
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5Apply temporary workaround mitigate
Inspect `coder config-ssh --dry-run` output before applying changes.パッチが適用されるまでの応急処置として、Inspect `coder config-ssh --dry-run` output before applying changes. を実施。回避策の副作用 (機能低下) を確認した上で。
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6Apply patch patch
Upgrade github.com/coder/coder/v2 to 2.29.17ステージング環境で 2.29.17 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
go
github.com/coder/coder/v2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.29.17"}]}]
References
- patch [email protected]
- patch [email protected]
- web https://github.com/advisories/GHSA-mcqq-fqgf-rxwm
- web [email protected]
- web [email protected]
- web [email protected]
- web [email protected]