CVE-2026-55078 Coder vulnerability
Coder allows organizations to provision remote development environments via Terraform. Starting in version 2.17.0 and prior to versions 2.29.17, 2.32.7, 2.33.8, and 2.34.2, `POST /api/v2/files` converts zip uploads to tar in memory via `CreateTarFromZip`, which enforced a per-entry size limit but no aggregate limit on total decompressed output, writing to an unbounded in-memory buffer. Exploitation requires authenticated file-upload access and the impact is limited to availability (denial of service). The fix in versions 2.29.17, 2.32.7, 2.33.8, and 2.34.2 adds a metadata preflight check that sums projected entry sizes and a streaming writer that enforces the aggregate limit during decompression. As a workaround, restrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of `Coderd`.
Quick answer
Coder should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- >=2.34.0 <2.34.2
- >=2.33.0 <2.33.8
- >=2.30.0 <2.32.7
- >=2.17.0 <2.29.17
Fixed versions
- 2.29.17
- 2.32.7
- 2.33.8
- 2.34.2
How to fix it
CVE-2026-55078 affects Coder remote development deployments where zip uploads to /api/v2/files can be converted to tar in memory without an aggregate decompressed-size limit, allowing an authenticated file-upload user to exhaust Coderd memory. Prioritize internet-facing, shared, or multi-tenant Coder environments because compromise can affect developer workspaces, identity flows, tokens, or control-plane availability depending on the issue. Upgrade to Coder 2.29.17, 2.32.7, 2.33.8, and 2.34.2, or a later supported release on the relevant branch, because those are the vendor-supported patched versions. Restrict file-upload permissions to trusted users and enforce reverse-proxy request body limits until the patched Coder release is deployed.
- Inventory all Coder servers, workspace proxies, provisioner daemons, AI Bridge components, templates, and CLI installations across production, staging, and developer environments.
- Identify affected Coder versions and compare every deployment with the fixed releases for CVE-2026-55078: 2.29.17, 2.32.7, 2.33.8, and 2.34.2.
- Upgrade Coder servers and related components to the patched release for the installed branch, then roll updated CLI or automation binaries where they are part of the affected workflow.
- Restrict file-upload permissions to trusted users and enforce reverse-proxy request body limits until the patched Coder release is deployed.
- Review Coder role bindings, OIDC settings, API keys, template parameters, provisioner access, workspace app exposure, and reverse proxy rules for unnecessary trust or public reachability.
- Review Coder audit logs, reverse proxy logs, provisioner logs, and workspace events for suspicious requests matching the affected endpoint or workflow.
- If exploitation or credential exposure is suspected, revoke affected sessions, rotate API keys and workspace tokens, preserve audit evidence, and rebuild workspaces or hosts whose integrity cannot be trusted.
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Verify the fix
- Confirm every affected Coder component reports a patched version for CVE-2026-55078: 2.29.17, 2.32.7, 2.33.8, and 2.34.2, or a later supported release.
- Confirm upload and decompression paths enforce aggregate size limits before large in-memory buffers can be allocated.
- Confirm temporary restrictions, role changes, OIDC settings, proxy ACLs, and API-key revocations match the intended least-privilege policy.
- Review logs after patching to confirm exploit attempts are blocked or fail safely without exposing credentials, internal network details, or control-plane availability.
- Document patched versions, configuration changes, remaining exceptions, and evidence, then rerun Fixnx or the relevant vulnerability scan where applicable.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-55078?
Coder versions listed as affected should be reviewed: >=2.34.0 <2.34.2, >=2.33.0 <2.33.8, >=2.30.0 <2.32.7, >=2.17.0 <2.29.17.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.