Linux: >> Linux Kernel >> 6.18.41 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: prevent path traversal bypass by restricting caseless retry
ksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path
resolution within the share root. When a crafted path attempts to
escape the share boundary using parent-directory components ('..'),
vfs_path_parent_lookup() detects this and immediately fails,
returning -EXDEV.
However, a bug exists in __ksmbd_vfs_kern_path() under caseless mode.
The function fails to intercept the -EXDEV error and erroneously
falls through to the caseless retry logic, which is intended only
for genuinely missing files. During this retry process, the path
is reconstructed, leading to an unintended LOOKUP_BENEATH bypass
that allows write-capable users to create zero-length files or
directories outside the exported share.
Fix this by ensuring that the execution only proceeds to the caseless
lookup retry when the error is specifically -ENOENT. Any other errors,
such as -EXDEV from a path traversal attempt, must be returned immediately.
CVSS Score
8.6
EPSS Score
0.004
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
smb/client: fix chown/chgrp with SMB3 POSIX Extensions
Ownership (chown) and group (chgrp) modifications were being ignored when
mounting with SMB3 POSIX Extensions unless CIFS_MOUNT_CIFS_ACL or
CIFS_MOUNT_MODE_FROM_SID were also explicitly set.
Fix this by checking for posix_extensions in cifs_setattr_nounix() when
updating UID and GID, ensuring that id_mode_to_cifs_acl() is called to map
and set the ownership/group information on the server.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
USB: iowarrior: fix use-after-free on disconnect race
mutex_unlock() may access the mutex structure after releasing the lock
and therefore cannot be used to manage lifetime of objects directly
(unlike spinlocks and refcounts). [1][2]
Use a kref to release the driver data to avoid use-after-free in
mutex_unlock() when release() races with disconnect().
[1] a51749ab34d9 ("locking/mutex: Document that mutex_unlock() is non-atomic")
[2] 2b9d9e0a9ba0 ("locking/mutex: Clarify that mutex_unlock(), and most
other sleeping locks, can still use the lock object
after it's unlocked")
CVSS Score
7.8
EPSS Score
0.001
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt76: mt7921/mt7925: fix NULL dereference in CSA beacon
This patch is based on a BUG as reported by Bongani Hlope at
https://lore.kernel.org/all/20260502125824.425d7159@bongani-mini.home.org.za/
When a channel-switch announcement (CSA) beacon is received,
cfg80211 queues a wiphy work item that eventually calls
mt7921_channel_switch_rx_beacon(). If the station disconnects
(or the channel context is otherwise torn down) between the
time the work is queued and the time it runs, the driver's
dev->new_ctx pointer can already have been cleared to NULL.
mt7921_channel_switch_rx_beacon() then dereferences new_ctx
unconditionally, triggering a NULL pointer dereference at
address 0x0:
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:mt7921_channel_switch_rx_beacon+0x1f/0x100 [mt7921_common]
The same missing guard exists in mt7925_channel_switch_rx_beacon(),
which shares the same code pattern introduced by the same commit.
Add an early-return NULL check for dev->new_ctx in both
mt7921_channel_switch_rx_beacon() and
mt7925_channel_switch_rx_beacon(). When new_ctx is NULL there is
no pending channel switch to process, so returning immediately is
the correct and safe action.
Oops-Analysis: http://oops.fenrus.org/reports/lkml/20260502125824.425d7159@bongani-mini.home.org.za/report.html
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
KVM: guest_memfd: Treat memslot binding offset+size as unsigned values
When binding a memslot to a guest_memfd file, treat the offset and size as
unsigned values to fix a bug where the sum of the two can result in a false
negative when checking for overflow against the size of the file. Passing
unsigned values also avoids relying on somewhat obscure checks in other
flows for safety, and tracks the offset and size as they are intended to be
tracked, as unsigned values.
On 64-bit kernels, the number of pages a memslot contains and thus the size
(and offset) of its guest_memfd binding are unsigned 64-bit values. Taking
the offset+size as an loff_t instead of a uoff_t inadvertently converts
the unsigned value to a signed value if the offset and/or size is massive.
Locally storing the offset and size as signed values is benign in and of
itself (though even that is *extremely* difficult to discern), but
operating on their sum is not.
For the offset, KVM explicitly checks against a negative value, which might
seem like a bug as KVM could incorrectly reject a legitimate binding, but
that's not actually the case as KVM_CREATE_GUEST_MEMFD takes a signed value
for its size, i.e. a would-be-negative offset is also greater than the
maximum possible size of any guest_memfd file.
Regarding the size, while KVM lacks an explicit check for a negative value,
i.e. seemingly has a flawed overflow check, KVM restricts the number of
pages in a single memslot to the largest positive signed 32-bit value:
if (id < KVM_USER_MEM_SLOTS &&
(mem->memory_size >> PAGE_SHIFT) > KVM_MEM_MAX_NR_PAGES)
return -EINVAL;
and so that maximum "size" will ever be is 0x7fffffff000.
The sum of the two is, however, problematic. While the size is restricted
by KVM's memslot logic, the offset is not, i.e. the offset is completely
unchecked until the "offset + size > i_size_read(inode)" check. If the
offset is the (nearly) largest possible _positive_ value, then adding size
to the offset can result in a signed, negative 64-bit value. When compared
against the size of the file (guaranteed to be positive), the negative sum
is always smaller, and KVM incorrectly allows the absurd offset.
Opportunistically add missing includes in kvm_mm.h (instead of relying on
its parents).
CVSS Score
7.0
EPSS Score
0.001
Published
2026-07-25
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: xsk: Fix unlocked writing to ICOSQ
During napi poll, when the affinity changes and there's still XSK work
to be done, we trigger an ICOSQ interrupt on the new CPU. However, this
triggering on the ICOSQ is done unprotected.
There are 2 such races:
A) mlx5e_trigger_irq() is called while mlx5e_xsk_alloc_rx_mpwqe() is
running from a different CPU due to affinity change. This can happen
because IRQ triggering is done after napi_complete_done(). At this point
the NAPI can be scheduled on a different CPU. Like this:
CPU A (old affinity, NAPI tail) CPU B (new affinity, fresh NAPI)
------------------------------- --------------------------------
napi_complete_done() clears SCHED
mlx5e_cq_arm(...)
napi_schedule_prep() sets SCHED
mlx5e_napi_poll()
mlx5e_xsk_alloc_rx_mpwqe()
mlx5e_icosq_sync_lock() // noop
memcpy 640 B UMR body
advance sq->pc by 10
mlx5e_trigger_irq(&c->icosq)
wqe_info[pi] = {NOP, 1}
mlx5e_post_nop() advances sq->pc
B) mlx5e_trigger_irq() is called on the ICOSQ when
mlx5e_trigger_napi_icosq() is running.
The obvious fix would be to lock the ICOSQ. But ICOSQ has an optimized
locking scheme that doesn't work for this scenario. Kick the async ICOSQ
instead which is always locked.
This issue was noticed in the wild with the following splat:
netdevice: ge-0-0-1: Bad OP in ICOSQ CQE: 0xd
WARNING: drivers/net/ethernet/mellanox/mlx5/core/en_rx.c:826 [...]
[...]
Call Trace:
<IRQ>
mlx5e_napi_poll+0x11d/0x7f0 [mlx5_core]
__napi_poll+0x30/0x200
? skb_defer_free_flush+0x9c/0xc0
net_rx_action+0x2fe/0x3f0
handle_softirqs+0xd8/0x340
__irq_exit_rcu+0xbc/0xe0
common_interrupt+0x85/0xa0
</IRQ>
<TASK>
asm_common_interrupt+0x26/0x40
[...]
---[ end trace 0000000000000000 ]---
mlx5_core 0000:08:00.0 ge-0-0-1: Error cqe on cqn 0x548, ci 0x2022, qn 0x8f4,
opcode 0xd, syndrome 0x2, vendor syndrome 0x68
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000030: 00 00 00 00 01 00 68 02 01 00 08 f4 de 14 59 d2
WQE DUMP: WQ size 16384 WQ cur size 0, WQE index 0x1e14, len: 64
00000000: 00 00 00 01 d9 ed 80 02 00 00 00 01 d9 ed 90 02
00000010: 00 00 00 01 d9 ed a0 02 00 00 00 01 d9 ed b0 02
00000020: 00 00 00 01 d9 ed c0 02 00 00 00 01 d9 ed d0 02
00000030: 00 00 00 01 d9 ed e0 02 00 00 00 01 d9 ed f0 02
mlx5_core 0000:08:00.0 ge-0-0-1: Error cqe on cqn 0x548, ci 0x2023, qn 0x8f4,
opcode 0xd, syndrome 0x5, vendor syndrome 0xf9
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000030: 00 00 00 00 01 00 f9 05 01 00 08 f4 de 15 cf d2
CVSS Score
7.5
EPSS Score
0.003
Published
2026-07-24
In the Linux kernel, the following vulnerability has been resolved:
netfs: Fix potential for tearing in ->remote_i_size and ->zero_point
Fix potential tearing in using ->remote_i_size and ->zero_point by copying
i_size_read() and i_size_write() and using the same seqcount as for i_size.
We need to make sure that netfslib and the filesystems that use it always
hold i_lock whilst updating any of the sizes to prevent i_size_seqcount
from getting corrupted.
CVSS Score
9.8
EPSS Score
0.004
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
drm/msm/adreno: Fix a reference leak in a6xx_gpu_init()
In a6xx_gpu_init(), node is obtained via of_parse_phandle().
While there was a manual of_node_put() at the end of the
common path, several early error returns would bypass this call,
resulting in a reference leak.
Fix this by using the __free(device_node) cleanup handler to
release the reference when the variable goes out of scope.
Patchwork: https://patchwork.freedesktop.org/patch/700661/
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
netfs: Fix zeropoint update where i_size > remote_i_size
Fix the update of the zero point[*] by netfs_release_folio() when there is
uncommitted data in the pagecache beyond the folio being released but the
on-server EOF is in this folio (ie. i_size > remote_i_size). The update
needs to limit zero_point to remote_i_size, not i_size as i_size is a local
phenomenon reflecting updates made locally to the pagecache, not stuff
written to the server. remote_i_size tracks the server's i_size.
[*] The zero point is the file position from which we can assume that the
server will just return zeros, so we can avoid generating reads.
Note that netfs_invalidate_folio() probably doesn't need fixing as
zero_point should be updated by setattr after truncation or fallocate.
Found with:
fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \
/xfstest.test/junk --replay-ops=junk.fsxops
using the following as junk.fsxops:
truncate 0x0 0x1bbae 0x82864
write 0x3ef2e 0xf9c8 0x1bbae
write 0x67e05 0xcb5a 0x4e8f6
mapread 0x57781 0x85b6 0x7495f
copy_range 0x5d3d 0x10329 0x54fac 0x7495f
write 0x64710 0x1c2b 0x7495f
mapread 0x64000 0x1000 0x7495f
on cifs with the default cache option.
It shows read-gaps on folio 0x64 failing with a short read (ie. it hits
EOF) if the FMODE_READ check is commented out in netfs_perform_write():
if (//(file->f_mode & FMODE_READ) ||
netfs_is_cache_enabled(ctx)) {
and no fscache. This was initially found with the generic/522 xfstest.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
erofs: fix metabuf leak in inode xattr initialization
commit bb88e8da0025 ("erofs: use meta buffers for xattr operations")
converted xattr operations to use on-stack erofs_buf instances.
erofs_init_inode_xattrs() uses such a metabuf while reading the inline
xattr header and shared xattr id array.
Some error paths after erofs_read_metabuf() leave through out_unlock
without dropping the metabuf, so the folio reference can leak.
Consolidate the cleanup at out_unlock. erofs_put_metabuf() is a
no-op if no folio has been acquired, and this keeps all paths after
taking EROFS_I_BL_XATTR_BIT covered by a single cleanup site.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-19
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