CVE-2026-55078

### 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: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### 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!