CVE-2026-98126: smb/client: validate new EOF for zero range

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-25 · updated 2026-10-22
Weakness: CWE-770

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 products

Linux kernel: from 5.1 before 6.6.160; from 6.7 before 6.12.111; from 6.13 before 6.18.53; from 6.19 before 7.2.7; 7.3-rc1 — fixed in 6.12.111, 6.18.53, 6.6.160, 7.2.7

How to fix

Upgrade to a fixed version: Linux kernel 6.12.111, 6.18.53, 6.6.160, 7.2.7. Check the vendor advisory for mitigations.

References

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