CVE-2020-15113: Directories created via os.MkdirAll are not checked for permissions

### Vulnerability type Access Controls ### Detail etcd creates certain directory paths (etcd data directory and the directory path when provided to automatically generate self-signed certificates for TLS connections with clients) with restricted access permissions (700) by using the os.MkdirAll. This function does not perform any permission checks when a given directory path exists already. ### Specific Go Package Affected github.com/etcd-io/etcd/pkg/fileutil ### Workarounds Make sure these directories have the desired permit (700). ### References Find out more on this vulnerability in the [security audit report](https://github.com/etcd-io/etcd/blob/master/security/SECURITY_AUDIT.pdf) ### For more information If you have any questions or comments about this advisory: * Contact the [etcd security committee](https://github.com/etcd-io/etcd/blob/master/security/security-release-process.md#product-security-committee-psc)

Ubuntu Security Notice 5628-1 - It was discovered that etcd incorrectly handled certain specially crafted WAL files. An attacker could possibly use this issue to cause a denial of service. It was discovered that etcd incorrectly handled directory permissions when trying to create a directory that exists already. An attacker could possibly use this issue to obtain sensitive information. It was discovered that etcd incorrectly handled endpoint setup. An attacker could possibly use this issue to cause a denial of service.