# GHSA-x9qq-236j-gj97: If a user has restricted access to a project that is configured with `restricted=true`, they can gain root access on the system > A low-privileged user in a restricted LXD project can gain root access by creating a disk device with shift enabled, bypassing path restrictions. - **Severity:** Not scored - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 5 Dec 2023 ## What is GHSA-x9qq-236j-gj97? GHSA-x9qq-236j-gj97 is a vulnerability in github.com/canonical/lxd, published on 5 Dec 2023. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description ### Summary If a user has restricted access to a project that is configured with `restricted=true`, they can gain root access on the system by creating a disk device with `shift=true` and creating a setuid root executable. This is possible because the `shift` property is not restricted unless `restricted.devices.disk.paths` is set. ### Details The following patch shows the offending code with a possible fix: ```patch --- a/lxd/device/disk.go +++ b/lxd/device/disk.go @@ -429,17 +429,19 @@ func (d *disk) validateEnvironmentSourcePath() error { if instProject.Name != api.ProjectDefaultName { // If restricted disk paths are in force, then check the disk's source is allowed, and record the // allowed parent path for later user during device start up sequence. - if shared.IsTrue(instProject.Config["restricted"]) && instProject.Config["restricted.devices.disk.paths"] != "" { - allowed, restrictedParentSourcePath := project.CheckRestrictedDevicesDiskPaths(instProject.Config, d.config["source"]) - if !allowed { - return fmt.Errorf("Disk source path %q not allowed by project for disk %q", d.config["source"], d.name) + if shared.IsTrue(instProject.Config["restricted"]) { + if instProject.Config["restricted.devices.disk.paths"] != "" { + allowed, restrictedParentSourcePath := project.CheckRestrictedDevicesDiskPaths(instProject.Config, d.config["source"]) + if !allowed { + return fmt.Errorf("Disk source path %q not allowed by project for disk %q", d.config["source"], d.name) + } + + d.restrictedParentSourcePath = shared.HostPath(restrictedParentSourcePath) } if shared.IsTrue(d.config["shift"]) { return fmt.Errorf(`The "shift" property cannot be used with a restricted source path`) } - - d.restrictedParentSourcePath = shared.HostPath(restrictedParentSourcePath) } } ``` ### PoC ```bash $ lxc project create restricted -c restricted=true -c restricted.devices.disk=allow $ lxc project switch restricted $ lxc profile device add default root disk path=/ pool=default $ lxc init ubuntu:22.04 c1 $ lxc config device add c1 d1 disk source=/ path=/mnt shift=true $ lxc start c1 # no error $ lxc project set restricted restricted.devices.disk.paths=/ # explicitly allow mounting / $ lxc restart c1 Error: Failed to start device "d1": The "shift" property cannot be used with a restricted source path ``` Created https://github.com/canonical/lxd/issues/12606 to improve the documentation as per https://github.com/canonical/lxd/security/advisories/GHSA-x9qq-236j-gj97#advisory-comment-91918 ## Which versions are affected by GHSA-x9qq-236j-gj97? 4 open source packages ship an affected version, including github.com/canonical/lxd. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `github.com/canonical/lxd` | Go | From 0.0.0-20230920084527-cbe39c5d3f14 | 0.0.0-20240118092008-ce1bd0dd37bb | | `github.com/canonical/lxd` | Go | From 0.0.0-20230920084527-cbe39c5d3f14 | 0.0.0-20240118092008-ce1bd0dd37bb | | `github.com/canonical/lxd` | Go | From 5.19.0 | 5.20.0 | | `github.com/canonical/lxd` | Go | From 5.19.0 | 5.20.0 | ## How do I fix GHSA-x9qq-236j-gj97? Upgrade github.com/canonical/lxd to a fixed version for your release line: 0.0.0-20240118092008-ce1bd0dd37bb or 5.20.0. ## Is GHSA-x9qq-236j-gj97 being exploited? There is no known exploitation of GHSA-x9qq-236j-gj97 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for GHSA-x9qq-236j-gj97 and fix it if it is affected. What it is: GHSA-x9qq-236j-gj97 is a vulnerability in github.com/canonical/lxd, published on 5 Dec 2023. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of GHSA-x9qq-236j-gj97 in the wild and no public exploit code. Affected packages and fixed versions: - github.com/canonical/lxd (Go): affected from 0.0.0-20230920084527-cbe39c5d3f14; fixed in 0.0.0-20240118092008-ce1bd0dd37bb - github.com/canonical/lxd (Go): affected from 0.0.0-20230920084527-cbe39c5d3f14; fixed in 0.0.0-20240118092008-ce1bd0dd37bb - github.com/canonical/lxd (Go): affected from 5.19.0; fixed in 5.20.0 - github.com/canonical/lxd (Go): affected from 5.19.0; fixed in 5.20.0 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/GHSA-x9qq-236j-gj97/ (Markdown: https://insights.sbomify.com/GHSA-x9qq-236j-gj97/index.md) ``` ## Sources - OSV: https://osv.dev/vulnerability/GHSA-x9qq-236j-gj97 --- From sbomify Insights: https://insights.sbomify.com/GHSA-x9qq-236j-gj97/ Summaries are generated and may contain mistakes; the official description above is the record.