CVE-2026-98126

smb/client: validate new EOF for zero range

MEDIUM
5.5
CVSS Score
Published: September 25, 2026 at 10:36 AM UTC
Updated: October 22, 2026 at 04:02 PM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.1%

Description

In the Linux kernel, the following vulnerability has been resolved: smb/client: validate new EOF for zero range When FALLOC_FL_ZERO_RANGE is used without FALLOC_FL_KEEP_SIZE, smb3_zero_range() may extend EOF without checking RLIMIT_FSIZE, allowing the file to grow beyond the caller's file-size limit. Fix this by calling inode_newsize_ok() before sending the zero-range request when the operation would extend EOF. Reproducer, using a file on a CIFS mount: bash -c ' FILE=/mnt/cifs/repro trap "" SIGXFSZ ulimit -f 3072 truncate -s 2M "$FILE" fallocate --zero-range -o 0 -l 4M "$FILE" echo "fallocate rc=$?" stat -c "file size=%s" "$FILE" ' Before this change, the operation succeeds despite the 3 MiB limit: fallocate rc=0 file size=4194304 After this change, fallocate fails and leaves the file at 2 MiB.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.1 ≤ v < 6.6.1606.13 ≤ v < 6.18.536.19 ≤ v < 7.2.76.7 ≤ v < 6.12.1115.17.372c419d9b073628d3b5b0b2fc787b724f1a8c726
Vendor states this is fixed in 06a4f9049cb6dc319bceec2dc813ba89add8b828 (fixed)
Vendor states this is fixed in 3673f057b64abfa957e8ae84448db69369a5091a (fixed)
Vendor states this is fixed in 88972e35750792e717af287dc71f42a03b5cbce4 (fixed)
Vendor states this is fixed in f320ca20c273a26cd779bdb2b2e4b076a95c76f6 (fixed)
Vendor states this is fixed in 5.1 (unaffected)
Vendor states this is fixed in 6.12.111 (unaffected)
Vendor states this is fixed in 6.18.53 (unaffected)
Vendor states this is fixed in 6.6.160 (unaffected)
Vendor states this is fixed in 7.2.7 (unaffected)
Vendor states this is fixed in 7.3 (unaffected)
Vendor states this is fixed in 7.3-rc2 (unaffected)

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-770

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