{"id":"CVE-2026-55078","aliases":["GHSA-2mg2-p7r7-g27f","GO-2026-5916"],"url":"https://o3.security/vulnerability/CVE-2026-55078","summary":"Coder: Zip upload decompression lacks aggregate size limit, enabling denial of service","details":"### Summary\n\n`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.\n\n> **Note:** Exploitation requires authenticated file-upload access and the impact is limited to availability (denial of service).\n\n### Impact\n\nAn 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.\n\n### Patches\n\nThe fix adds a metadata preflight check that sums projected entry sizes and a streaming writer that enforces the aggregate limit during decompression.\n\nThe fix was backported to all supported release lines:\n\n| Release line | Patched version |\n|---|---|\n| 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) |\n| 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) |\n| 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) |\n| 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) |\n\n### Workarounds\n\nRestrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of `coderd`.\n\n### Resources\n\n- Fix: #25877\n\n### Credits\n\nCoder would like to thank Anthropic's Security Team (ANT-2026-22438) for independently disclosing this issue!","published":"2026-07-07T22:47:07.079Z","modified":"2026-10-21T02:31:01.626393028Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00602,"percentile":0.4722,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/coder/coder/v2","fixedVersion":"2.34.2"},{"ecosystem":"Go","name":"github.com/coder/coder/v2","fixedVersion":"2.33.8"},{"ecosystem":"Go","name":"github.com/coder/coder/v2","fixedVersion":"2.32.7"},{"ecosystem":"Go","name":"github.com/coder/coder/v2","fixedVersion":"2.29.17"}],"fix":{"url":"https://github.com/coder/coder/pull/25877","label":"coder/coder#25877"},"references":[{"type":"WEB","url":"https://github.com/coder/coder/releases/tag/v2.29.17"},{"type":"WEB","url":"https://github.com/coder/coder/releases/tag/v2.32.7"},{"type":"WEB","url":"https://github.com/coder/coder/releases/tag/v2.33.8"},{"type":"WEB","url":"https://github.com/coder/coder/releases/tag/v2.34.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55078.json"},{"type":"ADVISORY","url":"https://github.com/coder/coder/security/advisories/GHSA-2mg2-p7r7-g27f"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55078"},{"type":"FIX","url":"https://github.com/coder/coder/pull/25877"},{"type":"PACKAGE","url":"https://github.com/coder/coder"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:31:01.626393028Z"}}