---
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: 0.46939
---

## Overview

### 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!

## Affected packages

- `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`

## Remediation

Upgrade to a patched release:

- `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`