CVE-2023-43636 is a high-severity (CVSS 8.8) CWE-345 vulnerability in github.com/lf-edge/eve/pkg/grub. A fix is available for github.com/lf-edge/eve/pkg/grub — see the affected versions and patch details below.
Rootfs Not Protected
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 CVE-2023-43636.
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
CVE-2023-43636 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 378,156 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
github.com/lf-edge/eve/pkg/grubReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
In EVE OS, the “measured boot” mechanism prevents a compromised device from accessing the encrypted data located in the vault.
As per the “measured boot” design, the PCR values calculated at different stages of the boot process will change if any of their respective parts are changed.
This includes, among other things, the configuration of the bios, grub, the kernel cmdline, initrd, and more.
However, this mechanism does not validate the entire rootfs, so an attacker can edit the filesystem and gain control over the system.
As the default filesystem used by EVE OS is squashfs, this is somewhat harder than an ext4, which is easily changeable.
This will not stop an attacker, as an attacker can repackage the squashfs with their changes in it and replace the partition altogether.
This can also be done directly on the device, as the “003-storage-init” container contains the “mksquashfs” and “unsquashfs” binaries (with the corresponding libs).
An attacker can gain full control over the device without changing the PCR values, thus not triggering the “measured boot” mechanism, and having full access to the vault.
Note:
This issue was partially fixed in these commits (after disclosure to Zededa), where the config partition measurement was added to PCR13:
• aa3501d6c57206ced222c33aea15a9169d629141
• 5fef4d92e75838cc78010edaed5247dfbdae1889.
This issue was made viable in version 9.0.0 when the calculation was moved to PCR14 but it was not included in the measured boot.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/lf-edge/eve/pkg/grub | all versions | 0.0.0-20220708121648-5fef4d92e758go get github.com/lf-edge/eve/pkg/grub@v0.0.0-20220708121648-5fef4d92e758 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/lf-edge/eve/pkg/grub, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/lf-edge/eve/pkg/grub to 0.0.0-20220708121648-5fef4d92e758 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-43636 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 CVE-2023-43636 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-43636. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-43636 in your dependencies?
O3 Security finds CVE-2023-43636 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.