CVE-2026-23147 btrfs: zlib: fix the folio leak on S390 hardware acceleration
A memory leak in the Linux kernel's btrfs zlib module on S390 hardware can lead to resource exhaustion and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-23147?
CVE-2026-23147 is a medium-severity denial of service vulnerability in Linux kernel, published on 14 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
btrfs: zlib: fix the folio leak on S390 hardware acceleration
[BUG] After commit aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration buffer preparation"), we no longer release the folio of the page cache of folio returned by btrfs_compress_filemap_get_folio() for S390 hardware acceleration path.
[CAUSE] Before that commit, we call kumap_local() and folio_put() after handling each folio.
Although the timing is not ideal (it release previous folio at the beginning of the loop, and rely on some extra cleanup out of the loop), it at least handles the folio release correctly.
Meanwhile the refactored code is easier to read, it lacks the call to release the filemap folio.
[FIX] Add the missing folio_put() for copy_data_into_buffer().
Weakness: CWE-401
Which versions are affected by CVE-2026-23147?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23147?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-23147 being exploited?
There is no known exploitation of CVE-2026-23147 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-23147, DEBIAN-CVE-2026-23147, GHSA-h3fw-pc42-9f62, UBUNTU-CVE-2026-23147.