Distribution is a toolkit to pack, ship, store, and deliver container content. Systems running registry versions 3.0.0-beta.1 through 3.0.0-rc.2 with token authentication enabled may be vulnerable to an issue in which token authentication allows an attacker to inject an untrusted signing key in a JSON web token (JWT). The issue lies in how the JSON web key (JWK) verification is performed. When a JWT contains a JWK header without a certificate chain, the code only checks if the KeyID (`kid`) matches one of the trusted keys, but doesn't verify that the actual key material matches. A fix for the issue is available at commit 5ea9aa028db65ca5665f6af2c20ecf9dc34e5fcd and expected to be a part of version 3.0.0-rc.3. There is no way to work around this issue without patching if the system requires token authentication.

Local privilege escalation vulnerability in Ubuntu Kernels overlayfs ovl_copy_up_meta_inode_data skip permission checks when calling ovl_do_setxattr on Ubuntu kernels

A feature in LXD (LP#1829071), affects the default configuration of Ubuntu Server which allows privileged users in the lxd group to escalate their privilege to root without requiring a sudo password.

On Ubuntu kernels carrying both c914c0e27eb0 and "UBUNTU: SAUCE: overlayfs: Skip permission checking for trusted.overlayfs.* xattrs", an unprivileged user may set privileged extended attributes on the mounted files, leading them to be set on the upper files without the appropriate security checks.