CVE-2023-43636
HIGHCVE-2023-43636 is a high-severity (CVSS 8.8) CWE-345 vulnerability in github.com/lf-edge/eve/pkg/grub. O3 Security confirms whether CVE-2023-43636 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Rootfs Not Protected
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 | 0.0.0-20220708121648-5fef4d92e758 |
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. 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 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 pinpoints whether CVE-2023-43636 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 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 detects CVE-2023-43636 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.