GHSA-vf95-55w6-qmrf is a critical-severity (CVSS 10) CWE-61 vulnerability in youki. A fix is available for youki — see the affected versions and patch details below.
youki container escape and denial of service due to arbitrary write gadgets and procfs write redirects
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-vf95-55w6-qmrf.
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-vf95-55w6-qmrf 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 377,636 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
youkiReal-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
Impact
youki’s apparmor handling performs insufficiently strict write-target validation, which—combined with path substitution during pathname resolution—can allow writes to unintended procfs locations.
Weak write-target check
youki only verifies that the destination lies somewhere under procfs. As a result, a write intended for /proc/self/attr/apparmor/exec can succeed even if the path has been redirected to /proc/sys/kernel/hostname(which is also in procfs).
Path substitution While resolving a path component-by-component, a shared-mount race can substitute intermediate components and redirect the final target.
This is a different project, but the core logic is similar to the CVE in runc. Issues were identified in runc, and verification was also conducted in youki to confirm the problems. https://github.com/opencontainers/runc/security/advisories/GHSA-cgrx-mc8f-2prm
Credits
Thanks to Li Fubang (@lifubang from acmcoder.com, CIIC) and Tõnis Tiigi (@tonistiigi from Docker) for both independently discovering runc's original vulnerability, as well as Aleksa Sarai (@cyphar from SUSE) for the original research into this class of security issues and solutions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | youki | all versions | 0.5.7cargo update -p youki --precise 0.5.7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for youki, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update youki to 0.5.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vf95-55w6-qmrf 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-vf95-55w6-qmrf can be triaged on real exposure rather than presence alone.
Tailored to GHSA-vf95-55w6-qmrf. 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-vf95-55w6-qmrf in your dependencies?
O3 Security finds GHSA-vf95-55w6-qmrf across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.