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Fencer Vulns
medium 5.5

CVE-2025-22070 json

fs/9p: fix NULL pointer dereference on mkdir

published 2025-04-16 18 mo ago modified 2026-10-30 10 d ago also EUVD-2025-11220

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

fs/9p: fix NULL pointer dereference on mkdir

When a 9p tree was mounted with option 'posixacl', parent directory had a default ACL set for its subdirectories, e.g.:

setfacl -m default:group:simpsons:rwx parentdir

then creating a subdirectory crashed 9p client, as v9fs_fid_add() call in function v9fs_vfs_mkdir_dotl() sets the passed 'fid' pointer to NULL (since dafbe689736) even though the subsequent v9fs_set_create_acl() call expects a valid non-NULL 'fid' pointer:

[ 37.273191] BUG: kernel NULL pointer dereference, address: 0000000000000000 ... [ 37.322338] Call Trace: [ 37.323043] <TASK> [ 37.323621] ? __die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434) [ 37.324448] ? page_fault_oops (arch/x86/mm/fault.c:714) [ 37.325532] ? search_module_extables (kernel/module/main.c:3733) [ 37.326742] ? p9_client_walk (net/9p/client.c:1165) 9pnet [ 37.328006] ? search_bpf_extables (kernel/bpf/core.c:804) [ 37.329142] ? exc_page_fault (./arch/x86/include/asm/paravirt.h:686 arch/x86/mm/fault.c:1488 arch/x86/mm/fault.c:1538) [ 37.330196] ? asm_exc_page_fault (./arch/x86/include/asm/idtentry.h:574) [ 37.331330] ? p9_client_walk (net/9p/client.c:1165) 9pnet [ 37.332562] ? v9fs_fid_xattr_get (fs/9p/xattr.c:30) 9p [ 37.333824] v9fs_fid_xattr_set (fs/9p/fid.h:23 fs/9p/xattr.c:121) 9p [ 37.335077] v9fs_set_acl (fs/9p/acl.c:276) 9p [ 37.336112] v9fs_set_create_acl (fs/9p/acl.c:307) 9p [ 37.337326] v9fs_vfs_mkdir_dotl (fs/9p/vfs_inode_dotl.c:411) 9p [ 37.338590] vfs_mkdir (fs/namei.c:4313) [ 37.339535] do_mkdirat (fs/namei.c:4336) [ 37.340465] __x64_sys_mkdir (fs/namei.c:4354) [ 37.341455] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) [ 37.342447] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

Fix this by simply swapping the sequence of these two calls in v9fs_vfs_mkdir_dotl(), i.e. calling v9fs_set_create_acl() before v9fs_fid_add().

Patch / fix

  • Linux Linux 6.1.191, 6.6.160, 6.12.23, 6.13.11, 6.14.2, 6.15
  • linux Debian 14, Debian 13 6.12.25-1

debian advisories DEBIAN-CVE-2025-22070

  • linux Ubuntu 24.04 LTS 6.8.0-86.87
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1041.43
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1042.45
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1038.43
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1039.39
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1041.47
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1025.28
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1041.45

ubuntu advisories UBUNTU-CVE-2025-22070

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dtb-aarch64 openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-64kb SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-syms SLE Module for Development Tools 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-obs-qa openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-source SLE Module for Development Tools 15 SP6, SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-default SLE Workstation Extension 15 SP6, SLE Module for Legacy 15 SP6, SLE Module for Basesystem 15 SP6 +3 more 6.4.0-150600.23.53.1
  • kernel-kvmsmall openSUSE Leap 15.6 6.4.0-150600.23.53.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1

suse advisories SUSE-SU-2025:02000-1SUSE-SU-2025:01972-1SUSE-SU-2025:20413-1SUSE-SU-2025:01967-1SUSE-SU-2025:01965-1SUSE-SU-2025:01964-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-22070 updated cvss 5.5

kernel: fs/9p: fix NULL pointer dereference on mkdir

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
13 mo ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.