{"id":"CVE-2026-55079","aliases":["GHSA-f962-qm93-mj4c"],"title":"Coder's unbounded memory allocation in provisioner file upload allows authenticated denial of service","summary":"Coder's unbounded memory allocation in provisioner file upload allows authenticated denial of service","severity":"medium","cvss":4.9,"cwe":["CWE-789"],"vendor":"coder","product":"github.com/coder/coder/v2","ecosystem":"go","affected":["github.com/coder/coder/v2 >= 2.34.0, < 2.34.2","github.com/coder/coder/v2 >= 2.33.0, < 2.33.8","github.com/coder/coder/v2 >= 2.30.0, < 2.32.7","github.com/coder/coder/v2 >= 2.24.0, < 2.29.17"],"patched":["github.com/coder/coder/v2 2.34.2","github.com/coder/coder/v2 2.33.8","github.com/coder/coder/v2 2.32.7","github.com/coder/coder/v2 2.29.17"],"published":"2026-07-06","updated":"2026-07-06","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-f962-qm93-mj4c","references":[{"url":"https://github.com/coder/coder/security/advisories/GHSA-f962-qm93-mj4c"},{"url":"https://github.com/coder/coder/pull/25710"},{"url":"https://github.com/advisories/GHSA-f962-qm93-mj4c"}],"tags":["ghsa","go"],"ingestedAt":"2026-07-06T21:45:52.970Z","epss":0.00611,"epssPercentile":0.47602,"slug":"CVE-2026-55079","body":"## Overview\n\n### Summary\n\n`NewDataBuilder` in `provisionersdk/proto/dataupload.go` allocated a byte slice using the client-supplied `FileSize` from a `DataUpload` message without an upper-bound check. Although the DRPC wire limit is 4 MiB, the `FileSize` value itself was unconstrained\n\n### Impact\n\nAn authenticated user able to reach the provisioner daemon serve endpoint could send a roughly 50-byte message declaring a huge `FileSize` (for example 1 TiB), triggering an unrecoverable Go out-of-memory abort that terminates `coderd`. This is a single-message denial of service affecting the entire deployment.\n\n### Patches\n\nThe fix validates `FileSize` against an upper bound (`MaxFileSize = 100 MiB`) before allocation.\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 access to the provisioner daemon serve endpoint to trusted provisioner daemon service accounts.\n\n### Resources\n\n- Fix: #25710\n\n### Credits\n\nCoder would like to thank Anthropic's Security Team (ANT-2026-22442) for independently disclosing this issue!\n\n## Affected packages\n\n- `github.com/coder/coder/v2 >= 2.34.0, < 2.34.2`\n- `github.com/coder/coder/v2 >= 2.33.0, < 2.33.8`\n- `github.com/coder/coder/v2 >= 2.30.0, < 2.32.7`\n- `github.com/coder/coder/v2 >= 2.24.0, < 2.29.17`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/coder/coder/v2 2.34.2`\n- `github.com/coder/coder/v2 2.33.8`\n- `github.com/coder/coder/v2 2.32.7`\n- `github.com/coder/coder/v2 2.29.17`","depth":"sunlit","depthScore":27,"depthScoreParts":{"impact":27,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}