In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() installs an fd referencing a file from the lower filesystem without taking an additional reference to that file. After the btrfs ioctl completes
In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() installs an fd referencing a file from the lower filesystem without taking an additional reference to that file. After the btrfs ioctl completes this fd is closed, which then puts a reference to that file, leading to a refcount underflow.
| Vendor | Product | Versions |
|---|---|---|
| Ubuntu | Shiftfs in the Linux kernel | 5.3.0-11.12, 5.0 kernel |
Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.
For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.
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No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.