GHSA-f962-qm93-mj4c
Coder's unbounded memory allocation in provisioner file upload allows authenticated denial of service
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| 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 | >= 2.24.0, < 2.29.17 | 2.29.17 |
Details
As written in the advisory (Markdown source, shown as plain text).
### 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!
References
External links from the advisory. They lead to third-party sites.