CVE-2026-55078 coder CVE debrief

Who should care

Users of Coder versions 2.17.0 through 2.29.6, 2.32.6, 2.33.7, and 2.34.1 should assess and potentially update to patched versions 2.29.7, 2.32.7, 2.33.8, or 2.34.2. This includes operators, platform administrators, vulnerability management teams, and security teams responsible for ensuring the security and availability of Coder deployments.

Technical summary

CVE-2026-55078 is a denial-of-service vulnerability in Coder, affecting versions 2.17.0 through 2.29.6, 2.32.6, 2.33.7, and 2.34.1. The vulnerability arises from the `POST /api/v2/files` endpoint, which converts zip uploads to tar in memory. This process applies a per-entry size limit but lacks an aggregate limit on total decompressed output, leading to an unbounded in-memory buffer. Exploitation requires authenticated file-upload access, and the impact is limited to availability. The fix in versions 2.29.7, 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.

Defensive priority

Medium priority due to the requirement for authenticated access and the limited impact to availability.

Recommended defensive actions

• Update to Coder versions 2.29.7, 2.32.7, 2.33.8, or 2.34.2
• Restrict file-upload permissions to trusted users
• Implement a reverse proxy with request-body size limits
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability and patches. Coder's official releases and security advisories confirm the issue and fixes. Evidence is limited, and defenders should verify affected scope and vendor guidance. The vulnerability affects Coder versions 2.17.0 through 2.29.6, 2.32.6, 2.33.7, and 2.34.1. Exploitation requires authenticated file-upload access, and the impact is limited to availability (denial of service).

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.