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EUVD-2026-333843

2026-10-06T06:27:28.299307+00:00

EUVD-2026-333843

fkie_cve-2026-55079

2026-10-06T06:27:28.299343+00:00

Coder allows organizations to provision remote development environments via Terraform. Starting in version 2.24.0 and prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, `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. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 validates `FileSize` against an upper bound (`MaxFileSize = 100 MiB`) before allocation. As a workaround, restrict access to the provisioner daemon serve endpoint to trusted provisioner daemon service accounts.

GHSA-f962-qm93-mj4c — Coder's unbounded memory allocation in provisioner file upload allows authenticated denial of service

2026-10-06T06:27:28.299379+00:00

Affected: Go: github.com/coder/coder/v2

### Summary

`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

### Impact

An 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.

### Patches

The fix validates `FileSize` against an upper bound (`MaxFileSize = 100 MiB`) before allocation.

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 access to the provisioner daemon serve endpoint to trusted provisioner daemon service accounts.

### Resources

- Fix: #25710

### Credits

Coder would like to thank Anthropic's Security Team (ANT-2026-22442) for independently disclosing this issue!