CVE-2026-43188 [Medium] | Security Vulnerability in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: ceph: do not propagate page array emplacement errors as batch errors When fscrypt is enabled, move_dirty_folio_in_page_array() may fail because it needs to allocate bounce buffers to store the encrypted versions of each folio. Each folio beyond the first allocates its bounce buffer with GFP_NOWAIT. Failures are common (and expected) under this allocation mode; they should flush (not abort) the batch. However, ceph_process_folio_batch() uses the same `rc` variable for its own return code and for capturing the return codes of its routine calls; failing to reset `rc` back to 0 results in the error being propagated out to the main writeback loop, which cannot actually tolerate any errors here: once `ceph_wbc.pages` is allocated, it must be passed to ceph_submit_write() to be freed. If it survives until the next iteration (e.g. due to the goto being followed), ceph_allocate_page_array()'s BUG_ON() will oops the worker. Note that this failure mode is currently masked due to another bug (addressed next in this series) that prevents multiple encrypted folios from being selected for the same write. For now, just reset `rc` when redirtying the folio to prevent errors in move_dirty_folio_in_page_array() from propagating. Note that move_dirty_folio_in_page_array() is careful never to return errors on the first folio, so there is no need to check for that. After this change, ceph_process_folio_batch() no longer returns errors; its only remaining failure indicator is `locked_pages == 0`, which the caller already handles correctly.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-07	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-07

—

0.02%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.5

3.1

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

[email protected]

OS Trackers for CVE-2026-43188

vendor	priority	summary	link
`debian`	unimportant	CVE-2026-43188 unimportant priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2026-43188
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2026-43188
`suse`	medium	CVE-2026-43188 severity moderate: SUSE including 21 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 198 product×package rows across 39 product lines (SUSE Linux Enterprise High Availability Extension 15 SP7, SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, … (39 product lines)): Known Not Affected 198.	https://www.suse.com/security/cve/CVE-2026-43188/
`ubuntu`	medium	CVE-2026-43188 medium priority: Ubuntu including 161 source packages (linux, linux-allwinner-5.19, …), 1449 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 1048, ignored 169, not-affected 125, released 83, needed 19, needs-triage 5.	https://ubuntu.com/security/CVE-2026-43188

Affected software / configurations for CVE-2026-43188

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 6.15, < 6.18.16	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.19, < 6.19.6	cpe:2.3:o:linux:linux_kernel::::::::

References for CVE-2026-43188

URL	Tags
https://git.kernel.org/stable/c/4c0d84c788d89c167abf0bf84fd37890c4c84f08	Patch
https://git.kernel.org/stable/c/707104682e3c163f7c14cdd6b07a3e95fb374759	Patch
https://git.kernel.org/stable/c/746840c87d76b614b14d9337c466ff022fc49823	Patch

URL

CVE-2026-43188 | ceph: do not propagate page array emplacement errors as batch errors

Exploit prediction scoring system (EPSS) score for CVE-2026-43188

Common vulnerability scoring system (CVSS) metrics for CVE-2026-43188

Weakness enumeration for CVE-2026-43188

GitHub Security Advisory for CVE-2026-43188

OS Trackers for CVE-2026-43188

Affected software / configurations for CVE-2026-43188

References for CVE-2026-43188