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CVE-2026-98126

Linux: smb/client: validate new EOF for zero range

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.12%Chance of exploitation activity in the next 30 days, higher than 1% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in5fbd8848f2e25c8163896ec52863df2305a3bb63Also 3673f057b64abfa957e8ae84448db69369a5091a, 06a4f9049cb6dc319bceec2dc813ba89add8b828 and 1 moreCVE List
Published25 Sep 2026Updated 21 Oct 2026CVE List

What fixes it

  • 5fbd8848f2e25c8163896ec52863df2305a3bb63LinuxCVE List
  • 3673f057b64abfa957e8ae84448db69369a5091aLinuxCVE List
  • 06a4f9049cb6dc319bceec2dc813ba89add8b828LinuxCVE List
  • 88972e35750792e717af287dc71f42a03b5cbce4LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 12

  • Linuxaffected: 72c419d9b073628d3b5b0b2fc787b724f1a8c726 before 5fbd8848f2e25c8163896ec52863df2305a3bb63CVE List
  • Linuxaffected: 72c419d9b073628d3b5b0b2fc787b724f1a8c726 before 3673f057b64abfa957e8ae84448db69369a5091aCVE List
  • Linuxaffected: 72c419d9b073628d3b5b0b2fc787b724f1a8c726 before 06a4f9049cb6dc319bceec2dc813ba89add8b828CVE List
  • Linuxaffected: 72c419d9b073628d3b5b0b2fc787b724f1a8c726 before f320ca20c273a26cd779bdb2b2e4b076a95c76f6CVE List
  • Linuxaffected: 72c419d9b073628d3b5b0b2fc787b724f1a8c726 before 88972e35750792e717af287dc71f42a03b5cbce4CVE List
  • Linuxaffected: 5.1CVE List
  • Linuxunaffected: all versions before 5.1CVE List
  • Linuxunaffected: 6.6.160 through 6.6.*CVE List
  • Linuxunaffected: 6.12.111 through 6.12.*CVE List
  • Linuxunaffected: 6.18.53 through 6.18.*CVE List
  • Linuxunaffected: 7.2.7 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 5