CVE-2026-23147

btrfs: zlib: fix the folio leak on S390 hardware acceleration

Published Feb 14, 2026 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed

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().

Analysis

Technical impact

The vulnerability arises because the btrfs zlib compression path for S390 hardware acceleration fails to release a folio that the kernel temporarily holds. The missing folio_put call creates a memory leak that can grow over time, potentially exhausting memory resources and harming system stability.

Affected Systems

Linux vendors running the Linux kernel are affected. The issue applies to kernel versions that have not yet incorporated the fix located in commit aa60fe12b4f4. This includes Linux kernel 6.19 release candidates from rc1 through rc7 and any earlier kernels that remain patched only by this commit’s resolution.

Risk and Exploitability

The CVSS score of 5.5 indicates moderate severity, and the EPSS score of less than 1% suggests a low probability of exploitation. The vulnerability is not currently listed in KEV, implying no known active exploits. An attacker with local system or elevated privileges could trigger repeated btrfs compression on S390 hardware, leading to a gradual increase in memory usage. The attack vector is inferred to be local, as it requires interaction with the kernel’s compression subsystem.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`aa60fe12b4f49f49fc73e5023f8675e2df1f7805`	affected	< e80617a5e1c246da2f112a1a072cdd535046adfe
`aa60fe12b4f49f49fc73e5023f8675e2df1f7805`	affected	< 0d0f1314e8f86f5205f71f9e31e272a1d008e40b

Linux

affected

Version	Status	Constraints
`6.15`	affected	—
`0`	unaffected	< 6.15
`6.18.9`	unaffected	≤ 6.18.*
`6.19`	unaffected	≤ *

Configuration 1 [-]

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:6.19:rc1::::::
	cpe:2.3:o:linux:linux_kernel:6.19:rc2::::::
	cpe:2.3:o:linux:linux_kernel:6.19:rc3::::::
	cpe:2.3:o:linux:linux_kernel:6.19:rc4::::::
	cpe:2.3:o:linux:linux_kernel:6.19:rc5::::::
	cpe:2.3:o:linux:linux_kernel:6.19:rc6::::::
	cpe:2.3:o:linux:linux_kernel:6.19:rc7::::::

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[aa60fe12b4f49f49fc73e5023f8675e2df1f7805,e80617a5e1c246da2f112a1a072cdd535046adfe)`	affected	code_commit	—
`[aa60fe12b4f49f49fc73e5023f8675e2df1f7805,0d0f1314e8f86f5205f71f9e31e272a1d008e40b)`	affected	code_commit	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`6.15`	affected	generic	—
`[0,6.15)`	unaffected	generic	—
`[6.18.9,6.19.0)`	unaffected	semver	—
`[6.19,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Update the system’s Linux kernel to a version that contains the commit aa60fe12b4f4 addressing the folio leak.
Reboot the machine to load the updated kernel and ensure all services are using it.
Monitor overall memory consumption and limit use of S390 hardware acceleration until the update is applied or further guidance is released.

Generated by OpenCVE AI on April 17, 2026 at 19:36 UTC.

Tracking

Advisories

Source	ID	Title
Ubuntu USN	USN-8570-1	Linux kernel vulnerabilities
Ubuntu USN	USN-8594-1	Linux kernel (OEM) vulnerabilities
Ubuntu USN	USN-8604-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-8605-1	Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN	USN-8570-2	Linux kernel (Oracle) vulnerabilities
Ubuntu USN	USN-8669-1	Linux kernel (NVIDIA) vulnerabilities

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.129% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/0d0f1314e8f86f5205f71f9e31e272a1d008e40b
https://git.kernel.org/stable/c/e80617a5e1c246da2f112a1a072cdd535046adfe
https://lore.kernel.org/linux-cve-announce/2026021413-CVE-2026-23147-1f6d@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-23147
https://www.cve.org/CVERecord?id=CVE-2026-23147

History

Mar 17, 2026 9:15 PM Weaknesses updated. Affected versions updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-401
CPEs		cpe:2.3:o:linux:linux_kernel:6.19:rc1:::::: cpe:2.3:o:linux:linux_kernel:6.19:rc2:::::: cpe:2.3:o:linux:linux_kernel:6.19:rc3:::::: cpe:2.3:o:linux:linux_kernel:6.19:rc4:::::: cpe:2.3:o:linux:linux_kernel:6.19:rc5:::::: cpe:2.3:o:linux:linux_kernel:6.19:rc6:::::: cpe:2.3:o:linux:linux_kernel:6.19:rc7::::::

Feb 16, 2026 12:15 PM Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
References		https://lore.kernel.org/linux-cve-announce/2026021413-CVE-2026-23147-1f6d@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-23147 https://www.cve.org/CVERecord?id=CVE-2026-23147
Metrics	threat_severity `None`	cvssV3_1 `{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}` threat_severity `Low`

Feb 14, 2026 4:15 PM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
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().
Title		btrfs: zlib: fix the folio leak on S390 hardware acceleration
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/0d0f1314e8f86f5205f71f9e31e272a1d008e40b https://git.kernel.org/stable/c/e80617a5e1c246da2f112a1a072cdd535046adfe