Medium 5.5Published May 27, 2026

CVE-2026-45892ext4: drop extent cache after doing PARTIAL_VALID1 zeroout

Updated under an hour ago (Oct 26, 2026, 4:10 AM ET)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: ext4: drop extent cache after doing PARTIAL_VALID1 zeroout When splitting an unwritten extent in the middle and converting it to initialized in ext4_split_extent() with the EXT4_EXT_MAY_ZEROOUT and EXT4_EXT_DATA_VALID2 flags set, it could leave a stale unwritten extent. Assume we have an unwritten file and buffered write in the middle of it without dioread_nolock enabled, it will allocate blocks as written extent. 0 A B N [UUUUUUUUUUUU] on-disk extent U: unwritten extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDD--] D: valid data |<- ->| ----> this range needs to be initialized ext4_split_extent() first try to split this extent at B with EXT4_EXT_DATA_PARTIAL_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but ext4_split_extent_at() failed to split this extent due to temporary lack of space. It zeroout B to N and leave the entire extent as unwritten. 0 A B N [UUUUUUUUUUUU] on-disk extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDDZZ] Z: zeroed data ext4_split_extent() then try to split this extent at A with EXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and leave an written extent from A to N. 0 A B N [UUWWWWWWWWWW] on-disk extent W: written extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDDZZ] Finally ext4_map_create_blocks() only insert extent A to B to the extent status tree, and leave an stale unwritten extent in the status tree. 0 A B N [UUWWWWWWWWWW] on-disk extent W: written extent [UUWWWWWWWWUU] extent status tree [--DDDDDDDDZZ] Fix this issue by always cached extent status entry after zeroing out the second part.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: May 30, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from ddf854e59166533b0f46ba32cd6cd9aca3197d1b before 28db4bfc6f82fd20e2aadb7fc162244109a4eb31; from 58ddae5d77b1db3a27b891c75a8fa120239ac092 before f0931a5c17005a0c4fc35bd1a001245effc3354b; from d17857b4fb9ba5745b59be0ef38fd532991fccbf before d8ee559fccdef713f058cfe5f2c03dc9b18be3b1; from d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88 before c2ee51d684adca7645e4aa74adca13f6750390bc; from 7015fcf473796e1d2d876f241bd9e0c36f3d4eef before a1b962a821e7a52d48212ae269b45808b4411267; from 1bf6974822d1dba86cf11b5f05498581cf3488a2 before 6d882ea3b0931b43530d44149b79fcd4ffc13030	CNA record
linux linux_kernel linux:linux_kernel	6.1.167	NVD

References

https://git.kernel.org/stable/c/28db4bfc6f82fd20e2aadb7fc162244109a4eb31patch
https://git.kernel.org/stable/c/f0931a5c17005a0c4fc35bd1a001245effc3354bpatch
https://git.kernel.org/stable/c/d8ee559fccdef713f058cfe5f2c03dc9b18be3b1patch
https://git.kernel.org/stable/c/c2ee51d684adca7645e4aa74adca13f6750390bcpatch
https://git.kernel.org/stable/c/a1b962a821e7a52d48212ae269b45808b4411267patch
https://git.kernel.org/stable/c/6d882ea3b0931b43530d44149b79fcd4ffc13030patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.