GHSA-27vp-2mmc-vmh3
MEDIUMGHSA-27vp-2mmc-vmh3 is a medium-severity (CVSS 6.1) CWE-863 vulnerability in nono-cli. O3 Security confirms whether GHSA-27vp-2mmc-vmh3 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
nono: Sandbox escape on Linux via D-Bus: `systemd-run --user`
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-27vp-2mmc-vmh3.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-27vp-2mmc-vmh3 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 364,277 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
nono-cliReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The nono Landlock/seccomp policies allow access to local Unix domain sockets (concrete and abstract). This allows an easy sandbox escape by talking to the per-user systemd dbus socket.
Threat scenario: Running Aider, Claude Code, OpenCode or similar tools with "allow bash" policy so that it can invoke arbitrary host tools like make, gcc, etc. to write code.
Reproducer
Here, instead of running a tool like opencode or claude one can just invoke systemd-run, but this is something an agent could be tricked into doing:
$ cd ~/src/myproject
$ nono run -s --allow-cwd --profile claude-code -- \
systemd-run --user -q --wait --collect \
/bin/sh -c "echo oops > ~/Documents/escaped.txt"
$ cat /var/home/test/Documents/escaped.txt
oops
$
Impact
Complete sandbox escape. The unsandboxed sibling process can write anywhere the user can write, spawn arbitrary processes with network access, etc.
Maintainer Context
This issue allows a process running inside the sandbox to escape confinement by interacting with local user-scoped IPC mechanisms and regain the authority already held by the invoking user or service account.
The issue impacts the sandbox’s confinement and blast-radius reduction guarantees for agents and sandboxed tooling. However, exploitation does not provide privilege escalation, cross-user access, or host compromise beyond the permissions already available to the launcher outside the sandbox.
This issue affects the CLI policy layer and bundled sandbox profiles. The underlying core library nono does not ship with policy definitions or agent-facing confinement profiles by default, nor do the language SDKs.
This is considered a serious issue because an AI agent or untrusted command stream operating within the sandbox could abuse the bypass to perform unauthorized or destructive actions using the delegated authority of the launching user.
The root cause was incomplete mediation of local Unix domain socket access within affected sandbox policies. Support for restricting this behavior has since been added and the fix is available in the repository pending release.
CVSS rationale: exploitation requires execution within a locally launched sandboxed process using the authority already delegated by the invoking user or service account (AV:L/PR:L). The issue allows reliable bypass of sandbox confinement and policy guarantees, resulting in high integrity impact (I:H) and limited availability impact (A:L) through destructive actions within the launcher’s existing permissions. However, the issue does not provide privilege escalation, cross-user access, or a change in security scope (S:U).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | nono-cli | all versions | 0.55.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nono-cli. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update nono-cli to 0.55.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-27vp-2mmc-vmh3 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-27vp-2mmc-vmh3 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-27vp-2mmc-vmh3. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-27vp-2mmc-vmh3 in your dependencies?
O3 detects GHSA-27vp-2mmc-vmh3 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.