CVE-2026-72367

Description

In the Linux kernel, the following vulnerability has been resolved: iomap: guard io_size EOF trim against concurrent truncate underflow iomap: fix zero padding data issue in concurrent append writes changed ioend accounting so that io_size tracks only valid data within EOF. This trims io_size when a writeback range extends past end_pos: ioend->io_size += map_len; if (ioend->io_offset + ioend->io_size > end_pos) ioend->io_size = end_pos - ioend->io_offset; However, if end_pos ends up below ioend->io_offset, the subtraction becomes negative and is stored in size_t io_size, causing an unsigned wrap to a huge value. This can happen when writeback continues past byte-level EOF up to a block-aligned range, or when a concurrent truncate shrinks the file after end_pos was sampled in iomap_writeback_handle_eof(). A wrapped io_size can mislead append detection and corrupt completion-time size handling, since filesystem end_io paths consume io_size for decisions such as on-disk EOF updates and unwritten/COW completion ranges. Fix this by clamping io_size to zero when EOF has moved to or before the ioend start offset. This preserves the original intent of trimming io_size to valid in-EOF data while avoiding the underflow.

Why is this CVE medium priority?

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Status

Show unmaintained releases

Package	Ubuntu Release	Status

Patch details

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Package	Patch details

Severity score breakdown

CVSS version:

Base score 5.8 · Medium

Base metrics

Parameter	Value
Attack vector	Local
Attack complexity	Low
Attack requirements	Present
Privileges required	Low
User interaction	None
Vulnerable system - Confidentiality impact	None
Vulnerable system - Integrity impact	Low
Vulnerable system - Availability impact	High
Subsequent system - Confidentiality impact	None
Subsequent system - Integrity impact	None
Subsequent system - Availability impact	None

Scores

Parameter	Value
Base score	5.8 · Medium
Base + Threat score	-
Base + Environmental score	-
Base + Threat + Environmental score	-

Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

Base score 8.8 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Unchanged
Confidentiality impact	High
Integrity impact	High
Availability impact	High

Scores

Parameter	Value
Base score	8.8 · High
Exploitability score	-
Impact score	-

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

References

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