CVE-2026-89558
CVE-2026-89558 is a security vulnerability. O3 Security confirms whether CVE-2026-89558 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: md/raid10: fix still_degraded being inverted in raid10_sync_request() Commit fe6a19d40ceb ("md/md-bitmap: merge…
Description
In the Linux kernel, the following vulnerability has been resolved:
md/raid10: fix still_degraded being inverted in raid10_sync_request()
Commit fe6a19d40ceb ("md/md-bitmap: merge md_bitmap_start_sync() into bitmap_operations") converted still_degraded from int to bool, but inverted the assignment in the loop that checks whether the array will still be degraded after the current device is recovered: "still_degraded = 1" became "still_degraded = false".
As a result, recovering a device while another mirror is still missing calls md_bitmap_start_sync() with degraded == false, which clears bitmap bits that the still-missing device needs. When that device is re-added, its bitmap-based recovery finds the bits already cleared and skips every region written while the array was degraded, so it is marked In_sync while holding stale data: silent corruption.
Reproducer (raid10 near=2, 4 disks, internal bitmap):
- fail and remove one disk of each mirror pair
- write to the degraded array
- re-add both disks and let recovery finish
- "check" reports mismatch_cnt=262272 after 256 MiB of degraded writes and file contents differ; the second disk's "recovery" completes in milliseconds because everything is skipped
The same conversion in raid1 got it right (still_degraded = true). Restore the correct value.
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-2026-89558 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-2026-89558 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-2026-89558. 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-2026-89558 in your dependencies?
O3 detects CVE-2026-89558 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.