GHSA-2mg2-p7r7-g27f
MEDIUMCoder: Zip upload decompression lacks aggregate size limit, enabling denial of service
Blast Radius
github.com/coder/coder/v2🐹github.com/coder/coder/v2🐹github.com/coder/coder/v2🐹github.com/coder/coder/v2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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.
Note: Exploitation requires authenticated file-upload access and the impact is limited to availability (denial of service).
Impact
An authenticated user could upload a zip within the 100 MiB upload limit but containing many highly compressible entries whose decompressed size exhausted memory, crashing coderd before any RBAC check. Repeated requests could keep the service unavailable. This is a denial of service; it does not allow data disclosure or code execution.
Patches
The fix adds a metadata preflight check that sums projected entry sizes and a streaming writer that enforces the aggregate limit during decompression.
The fix was backported to all supported release lines:
Workarounds
Restrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of coderd.
Resources
- Fix: #25877
Credits
Coder would like to thank Anthropic's Security Team (ANT-2026-22438) for independently disclosing this issue!
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.34.0&&< 2.34.2 | 2.34.2 |
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.33.0&&< 2.33.8 | 2.33.8 |
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.30.0&&< 2.32.7 | 2.32.7 |
| 🐹Go | github.com/coder/coder/v2 | ≥ 2.17.0&&< 2.29.17 | 2.29.17 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/coder/coder/v2. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/coder/coder/v2 to 2.34.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2mg2-p7r7-g27f is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2mg2-p7r7-g27f is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2mg2-p7r7-g27f. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2mg2-p7r7-g27f in your dependencies?
O3 detects GHSA-2mg2-p7r7-g27f across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.