Summary
Vitess users with backup storage access can gain unauthorized access to production deployment environments
Workarounds
If maintainers intended to use an external decompressor then they can always specify that decompressor command in the --external-decompressor flag value for vttablet and vtbackup. That then overrides any value specified in the manifest file.
If maintainers did not intend to use an external decompressor, nor an internal one, then they can specify a value such as cat or tee in the --external-decompressor flag value for vttablet and vtbackup to ensure that a harmless command is always used.
References
Users can read more about the issue here: https://github.com/vitessio/vitess/issues/19459
Impact
Any user with read/write access to the backup storage location (e.g. an S3 bucket) can manipulate backup manifest files so that arbitrary code is later executed when that backup is restored. This can be used to provide that attacker with unintended/unauthorized access to the production deployment environment, allowing them to access information available in that environment as well as run any additional arbitrary commands there.
Untrusted input reaches a shell command, allowing arbitrary commands to run on the host. Typical impact: code execution in the application's environment.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Fixes are expected to be released with versions v23.0.3 and v22.0.4
See fix commit at https://github.com/vitessio/vitess/commit/4c0173293907af9cb942a6683c465c3f1e9fdb5c
Frequently Asked Questions
- What is CVE-2026-27965? CVE-2026-27965 is a high-severity OS command injection vulnerability in vitess.io/vitess (go), affecting versions <= 0.23.2. No fixed version is listed yet. Untrusted input reaches a shell command, allowing arbitrary commands to run on the host.
- Which versions of vitess.io/vitess are affected by CVE-2026-27965? vitess.io/vitess (go) versions <= 0.23.2 is affected.
- Is there a fix for CVE-2026-27965? No fixed version is listed for CVE-2026-27965 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2026-27965 exploitable, and should I be worried? Whether CVE-2026-27965 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
- What actually determines whether CVE-2026-27965 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.
- How do I fix CVE-2026-27965? No fixed version is listed yet. In the interim: Avoid passing untrusted input to shell commands. Use parameterized APIs or libraries that do not invoke a shell.