CVE-2026-89559
CVE-2026-89559 is a remote code execution vulnerability. O3 Security confirms whether CVE-2026-89559 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
In the Linux kernel, the following vulnerability has been resolved: libnvdimm/labels: Prevent integer overflow in __nd_label_validate() The on-media namespace index field nslot is…
Description
In the Linux kernel, the following vulnerability has been resolved:
libnvdimm/labels: Prevent integer overflow in __nd_label_validate()
The on-media namespace index field nslot is a u32 read from the DIMM label storage area. __nd_label_validate() bounds it against the config area size, but sizeof_namespace_label() returns unsigned, so the product nslot * label_size is evaluated in 32-bit and wraps modulo 2^32 before the comparison. A crafted nslot passes the bound and is then used as the loop trip count in nd_label_data_init(), whose memset() walks off the end of the config_size buffer: an out-of-bounds write.
The field is not trusted -- it comes from the medium, or from userspace via ND_CMD_SET_CONFIG_DATA. Evaluate the product in 64-bit so the bound check is exact; conforming labels are unaffected.
The check was safe when introduced by commit 4a826c83db4e ("libnvdimm: namespace indices: read and validate"): it multiplied by sizeof(struct nd_namespace_label), a size_t, so on a 64-bit build the product did not wrap. Commit 564e871aa66f ("libnvdimm, label: add v1.2 nvdimm label definitions") narrowed it to 32 bits when the label size became a runtime value read via sizeof_namespace_label().
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. 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.
Remediation status
No patched version of the affected component has shipped for CVE-2026-89559 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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-2026-89559 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-2026-89559. 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-2026-89559 in your dependencies?
O3 detects CVE-2026-89559 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.