CVE-2026-55078

Coder: Zip upload decompression lacks aggregate size limit, enabling denial of service

An authenticated user could upload a zip within the 100 MiB upload limit but containing many highly compressible entries whose decompressed size exhausted memory, crashing coderd before any RBAC check. Repeated requests could keep the service unavailable. This is a denial of service; it does not allow data disclosure or code execution.

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2026-55078 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.34.2, 2.33.8, 2.32.7, 2.29.17); upgrading removes the vulnerable code path.

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The fix adds a metadata preflight check that sums projected entry sizes and a streaming writer that enforces the aggregate limit during decompression.

The fix was backported to all supported release lines:

1. What is CVE-2026-55078? CVE-2026-55078 is a medium-severity allocation of resources without limits or throttling vulnerability in github.com/coder/coder/v2 (go), affecting versions >= 2.34.0, < 2.34.2. It is fixed in 2.34.2, 2.33.8, 2.32.7, 2.29.17. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2026-55078? CVE-2026-55078 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/coder/coder/v2 are affected by CVE-2026-55078? github.com/coder/coder/v2 (go) versions >= 2.34.0, < 2.34.2 is affected.
4. Is there a fix for CVE-2026-55078? Yes. CVE-2026-55078 is fixed in 2.34.2, 2.33.8, 2.32.7, 2.29.17. Upgrade to this version or later.
5. Is CVE-2026-55078 exploitable, and should I be worried? Whether CVE-2026-55078 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-55078 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-55078?
   • Upgrade github.com/coder/coder/v2 to 2.34.2 or later
   • Upgrade github.com/coder/coder/v2 to 2.33.8 or later
   • Upgrade github.com/coder/coder/v2 to 2.32.7 or later
   • Upgrade github.com/coder/coder/v2 to 2.29.17 or later

Other vulnerabilities in github.com/coder/coder/v2