CVE-2026-90277
In the Linux kernel, the following vulnerability has been resolved: md/md-llbitmap: prevent create failure bitmap UAF llbitmap_create() publishes mddev->bitmap before reading the bitmap superblock. This is needed because llbitmap_read_sb() can initialize a new bitmap and flush it through helpers that use mddev->bitmap. If llbitmap_read_sb() fails, the old cleanup dropped bitmap_info.mutex and freed llbitmap before clearing mddev->bitmap. Readers such as /proc/mdstat rely on bitmap_info.mutex to keep the bitmap pointer stable while collecting bitmap stats, so they could observe the stale pointer after the failed create path released the mutex. Clear mddev->bitmap while still holding bitmap_info.mutex, then free the failed llbitmap after dropping the mutex. This makes mutex-protected readers see either a live bitmap or no bitmap.
Affected versions
Linux kernel versions
6.18
and later are affected. Fixed in
6.18.52,
7.2.6,
7.3-rc1
and their respective stable series.
References
3 totalFrequently asked questions
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What is CVE-2026-90277?
CVE-2026-90277 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 6.18 onward and has been patched in 6.18.52, 7.2.6 and 7.3-rc1. CVE-2026-90277 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-90277?
Yes. CVE-2026-90277 has been patched. Fixed versions include 6.18.52, 7.2.6 and 7.3-rc1. If you are running Linux kernel 6.18 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-90277 actively exploited?
No. CVE-2026-90277 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.