Vulnerability in github.com/coder/coder/v2 (CVE-2026-55078)
Summary
Vulnerability in github.com/coder/coder/v2 (CVE-2026-55078). Risk of unauthorized operations or information disclosure. Exploitable via POST /api/v2/files. Mitigation: upgrade to 2.29.17 or later.
Original description
The description as published by the source.
Coder allows organizations to provision remote development environments via Terraform. Starting in version 2.17.0 and prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, POST /api/v2/files converts zip uploads to tar in memory via CreateTarFromZip, which enforced a per-entry size limit but no aggregate limit on total decompressed output, writing to an unbounded in-memory buffer. Exploitation requires authenticated file-upload access and the impact is limited to availability (denial of service). The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 adds a metadata preflight check that sums projected entry sizes and a streaming writer that enforces the aggregate limit during decompression. As a workaround, restrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of coderd.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
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 CVE-2026-55078 has been found in github.com/coder/coder/v2.
Attackers can target a specific entry point like POST /api/v2/files over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
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-2026-55078" on the vendor's site.
CVE-2026-55078 (github.com/coder/coder/v2) — CWE-409 / CVSS v3 6.5
Attack vector: remote (network-reachable) / no user interaction
Attack surface: POST /api/v2/files / CreateTarFromZip / coderd
Patched: 2.29.17 — apply immediately
Workaround: Restrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of coderd.
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 (CWE-409) exists in github.com/coder/coder/v2. Attackers reach the vulnerable code path via POST /api/v2/files.
Check the vendor advisory for the affected versions of github.com/coder/coder/v2. Attack surface: POST /api/v2/files / CreateTarFromZip / coderd.
Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure.
Update to 2.29.17.
Workaround: Restrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of coderd.
Search webserver/proxy logs for unusual POST /api/v2/files requests with malformed payloads or SQL meta-characters. 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
Concrete steps and command examples for SOC/SRE teams to execute in order
-
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。 -
2Hunt for indicators of compromise detect
grep 'POST /api/v2/files' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/v2/filesへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply temporary workaround mitigate
Restrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of `coderd`.パッチが適用されるまでの応急処置として、Restrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of
coderd. を実施。回避策の副作用 (機能低下) を確認した上で。 -
4Apply 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 2 で見つけた異常検知の続報チェックを含めること。
-
5Post-deployment verification verify
Replay attack against POST /api/v2/files on staging to confirm patch closes the vector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 2 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
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com