TI-2025-26044 Aliases CVE-2025-38709 GHSA-4rvm-hh4p-2jfj

loop: Avoid updating block size under exclusive owner

LOW 24Published 2025-09-04 · Updated 2026-11-05

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 5 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

In the Linux kernel, the following vulnerability has been resolved: loop: Avoid updating block size under exclusive owner Syzbot came up with a reproducer where a loop device block size is changed underneath a mounted filesystem. This causes a mismatch between the block device block size and the block size stored in the superblock causing confusion in various places such as fs/buffer.c. The particular issue triggered by syzbot was a warning in __getblk_slow() due to requested buffer size not matching block device block size. Fix the problem by getting exclusive hold of the loop device to change its block size. This fails if somebody (such as filesystem) has already an exclusive ownership of the block device and thus prevents modifying the loop device under some exclusive owner which doesn't expect it.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00155 4th percentileScored 2026-11-07

Fix Partial Linux (Linux): 6.1.191, 6.6.109, 6.12.43 +3Red Hat: 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Linux	Linux	4.14 and later	6.1.191, 6.6.109, 6.12.43, 6.15.11, 6.16.2, 6.17	Patch available	CNA

Linux VendorLinux Affected 4.14 and later Fixed in 6.1.191, 6.6.109, 6.12.43, 6.15.11, 6.16.2, 6.17 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:o:linux:linux_kernel::::::::	before 6.6.109; 6.7 to before 6.12.43; 6.13 to before 6.15.11; 6.16 to before 6.16.2	Vulnerable	Linux

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions before 6.6.109; 6.7 to before 6.12.43; 6.13 to before 6.15.11; 6.16 to before 6.16.2 Vulnerable ·Linux

Remediation

Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.109, 6.12.43, 6.15.11, 6.16.2, 6.17

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux 10	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 6	Affected	No fix planned: Out of support scope
Red Hat Enterprise Linux 7	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 8	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux 9	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2025-38709
2026-10-03 Alias added: GHSA-4rvm-hh4p-2jfj
2026-10-30 Fix available: Linux/Linux@46034518cae95db4abfde990c9ca1a0751855072, Linux/[email protected] · CNA
2026-10-30 1 new reference · CNA
2026-11-05 CISA SSVC decision points changed

References

Patch 5

Other 1

https://git.kernel.org/stable/c/46034518cae95db4abfde990c9ca1a0751855072

TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3

See all 15278 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences