CVE-2026-98126 is a vulnerability in Linux Kernel
Published on September 25, 2026
smb/client: validate new EOF for zero range
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.
Products Associated with CVE-2026-98126
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Affected Versions
Linux:- Version 72c419d9b073628d3b5b0b2fc787b724f1a8c726 and below 3673f057b64abfa957e8ae84448db69369a5091a is affected.
- Version 72c419d9b073628d3b5b0b2fc787b724f1a8c726 and below 06a4f9049cb6dc319bceec2dc813ba89add8b828 is affected.
- Version 72c419d9b073628d3b5b0b2fc787b724f1a8c726 and below f320ca20c273a26cd779bdb2b2e4b076a95c76f6 is affected.
- Version 72c419d9b073628d3b5b0b2fc787b724f1a8c726 and below 88972e35750792e717af287dc71f42a03b5cbce4 is affected.
- Version 5.1 is affected.
- Before 5.1 is unaffected.
- Version 6.12.111, <= 6.12.* is unaffected.
- Version 6.18.53, <= 6.18.* is unaffected.
- Version 7.2.7, <= 7.2.* is unaffected.
- Version 7.3-rc2, <= * is unaffected.