Linux: >> Linux Kernel >> 6.10.7 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
udf: reject descriptors with oversized CRC length
udf_read_tagged() skips CRC verification when descCRCLength +
sizeof(struct tag) exceeds the block size. A crafted UDF image can
set descCRCLength to an oversized value to bypass CRC validation
entirely; the descriptor is then accepted based solely on the 8-bit
tag checksum, which is trivially recomputable.
Reject such descriptors instead of silently accepting them. A
legitimate single-block descriptor should never have a CRC length that
exceeds the block.
CVSS Score
8.4
EPSS Score
0.001
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage
f2fs_need_dentry_mark() reads nat_entry flags without mutual exclusion
with the checkpoint path, which can result in an incorrect inode block
marking state. The scenario is as follows:
create & write & fsync 'file A' write checkpoint
- f2fs_do_sync_file // inline inode
- f2fs_write_inode // inode folio is dirty
- f2fs_write_checkpoint
- f2fs_flush_merged_writes
- f2fs_sync_node_pages
- f2fs_fsync_node_pages // no dirty node
- f2fs_need_inode_block_update // return true
- f2fs_fsync_node_pages // inode dirtied
- f2fs_need_dentry_mark //return true
- f2fs_flush_nat_entries
- f2fs_write_checkpoint end
- __write_node_folio // inode with DENT_BIT_SHIFT set
SPO, "fsck --dry-run" find inode has already checkpointed but still
with DENT_BIT_SHIFT set
The state observed by f2fs_need_dentry_mark() can differ from the state
observed in __write_node_folio() after acquiring sbi->node_write. The
root cause is that the semantics of IS_CHECKPOINTED and
HAS_FSYNCED_INODE are only guaranteed after the checkpoint write has
fully completed.
This patch moves set_dentry_mark() into __write_node_folio() and
protects it with the sbi->node_write lock.
CVSS Score
7.1
EPSS Score
0.001
Published
2026-07-19
In the Linux kernel, the following vulnerability has been resolved:
ipv4: account for fraggap on the paged allocation path
In __ip_append_data(), when the paged-allocation branch is taken,
alloclen and pagedlen are computed as
alloclen = fragheaderlen + transhdrlen;
pagedlen = datalen - transhdrlen;
datalen already includes fraggap, but the fraggap bytes carried over
from the previous skb are copied into the new skb's linear area at
offset transhdrlen by the subsequent skb_copy_and_csum_bits(). The
linear area is therefore undersized by fraggap bytes while pagedlen is
overstated by the same amount.
The non-paged branch sets alloclen to fraglen, which already accounts
for fraggap because datalen does. Bring the paged branch in line by
adding fraggap to alloclen and subtracting it from pagedlen.
After this adjustment, copy no longer collapses to -fraggap on the
paged path, so remove the stale comment describing that old arithmetic.
CVSS Score
7.8
EPSS Score
0.002
Published
2026-07-16
In the Linux kernel, the following vulnerability has been resolved:
vsock/virtio: fix zerocopy completion for multi-skb sends
When a large message is fragmented into multiple skbs, the zerocopy
uarg is only allocated and attached to the last skb in the loop.
Non-final skbs carry pinned user pages with no completion tracking,
so the kernel has no way to notify userspace when those pages are safe
to reuse. If the loop breaks early the uarg is never allocated at all,
leaking pinned pages with no completion notification.
Fix this by following the approach used by TCP: allocate the zerocopy
uarg (if not provided by the caller) before the send loop and attach
it to every skb via skb_zcopy_set(), which takes a reference per skb.
Each skb's completion properly decrements the refcount, and the
notification only fires after the last skb is freed.
On failure, if no data was sent, the uarg is cleanly aborted via
net_zcopy_put_abort().
This issue was initially discovered by sashiko while reviewing commit
1cb36e252211 ("vsock/virtio: fix MSG_ZEROCOPY pinned-pages accounting")
but was pre-existing.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-07-13
In the Linux kernel, the following vulnerability has been resolved:
af_unix: Set gc_in_progress to true in unix_gc().
Igor Ushakov reported that unix_gc() could run with gc_in_progress
being false if the work is scheduled while running:
Thread 1 Thread 2 Thread 3
-------- -------- --------
unix_schedule_gc() unix_schedule_gc()
`- if (!gc_in_progress) `- if (!gc_in_progress)
|- gc_in_progress = true |
`- queue_work() |
unix_gc() <----------------/ |
| |- gc_in_progress = true
... `- queue_work()
| |
`- gc_in_progress = false |
|
unix_gc() <---------------------------------------------'
|
... /* gc_in_progress == false */
|
`- gc_in_progress = false
unix_peek_fpl() relies on gc_in_progress not to confuse GC
by MSG_PEEK.
Let's set gc_in_progress to true in unix_gc().
CVSS Score
7.1
EPSS Score
0.001
Published
2026-07-04
In the Linux kernel, the following vulnerability has been resolved:
ipv6: account for fraggap on the paged allocation path
In __ip6_append_data(), when the paged-allocation branch is taken
(MSG_MORE / NETIF_F_SG / large fraglen), alloclen and pagedlen are
computed as
alloclen = fragheaderlen + transhdrlen;
pagedlen = datalen - transhdrlen;
datalen already includes fraggap (datalen = length + fraggap). When
fraggap is non-zero, this is not the first skb and transhdrlen is zero.
The fraggap bytes carried over from the previous skb are copied just past
the fragment headers in the new skb's linear area. The linear area is
therefore undersized by fraggap bytes while pagedlen is overstated by the
same amount, and the copy writes past skb->end into the trailing
skb_shared_info.
An unprivileged user can trigger this via a UDPv6 socket using
MSG_MORE together with MSG_SPLICE_PAGES.
The bad accounting was introduced by commit 773ba4fe9104 ("ipv6:
avoid partial copy for zc"). Before commit ce650a166335 ("udp6: Fix
__ip6_append_data()'s handling of MSG_SPLICE_PAGES"), the negative
copy value caused -EINVAL to be returned. That later commit allowed
MSG_SPLICE_PAGES to proceed in this case, making the corruption
triggerable.
The non-paged branch sets alloclen to fraglen, which already accounts
for fraggap because datalen does. Bring the paged branch in line by
adding fraggap to alloclen and subtracting it from pagedlen.
After this adjustment, copy no longer collapses to -fraggap on the
paged path, so remove the stale comment describing that old arithmetic.
Since a negative copy is no longer expected for a valid MSG_SPLICE_PAGES
case, remove the MSG_SPLICE_PAGES exception from the negative copy check.
CVSS Score
7.8
EPSS Score
0.003
Published
2026-07-04
In the Linux kernel, the following vulnerability has been resolved:
KVM: SEV: Require in-GHCB scratch area if GHCB v2+ is in use
As per the GHCB spec, when using GHCB v2+ require the software scratch area
to reside in the GHCB's shared buffer. Note, things like Page State Change
(PSC) requests _rely_ on this behavior, as the guest can't provide a length
when making the request, i.e. the size of the guest payload is bounded by
the size of the shared buffer.
Failure to force usage of the GHCB, and a slew of other flaws, lets a
malicious SNP guest corrupt host kernel heap memory, and leak host heap
layout information.
setup_vmgexit_scratch() allocates a buffer via kvzalloc(exit_info_2),
where exit_info_2 is guest-controlled. With exit_info_2=24, this yields
a 24-byte allocation in kmalloc-cg-32 (32-byte slab objects). The buffer
holds an 8-byte psc_hdr followed by 8-byte psc_entry structs, so only
entries[0] and entries[1] are in-bounds.
snp_begin_psc() validates end_entry against VMGEXIT_PSC_MAX_COUNT (253)
but NOT against the actual buffer size:
idx_end = hdr->end_entry;
if (idx_end >= VMGEXIT_PSC_MAX_COUNT) { // checks 253, not buffer
snp_complete_psc(svm, ...);
return 1;
}
for (idx = idx_start; idx <= idx_end; idx++) {
entry_start = entries[idx]; // OOB when idx >= 2
The guest sets end_entry=10+, causing the host to iterate entries[2+]
which are OOB into adjacent slab objects. For each OOB entry:
- The host reads 8 bytes (OOB READ / info leak oracle)
- If the data passes PSC validation, __snp_complete_one_psc() writes
cur_page = 1 or 512 into the entry (OOB WRITE, sev.c:3806)
- If validation fails, the error response reveals whether adjacent
memory is zero vs non-zero (information disclosure to guest)
The guest controls allocation size (exit_info_2), entry range
(cur_entry/end_entry), and can fire unlimited VMGEXITs to repeatedly
hit different slab positions.
By exploiting the variety of bugs, a malicious SEV-SNP guest can:
- OOB read adjacent kmalloc-cg-32 objects (heap layout disclosure)
- OOB write cur_page bits into adjacent objects (heap corruption)
- Trigger use-after-free conditions across VMGEXITs
E.g. with KASAN enabled, a single insmod of the PoC guest module
produces 73 KASAN reports:
BUG: KASAN: slab-out-of-bounds in snp_begin_psc+0x126/0x890
Read of size 8 at addr ffff888219ffb5e0 by task qemu-system-x86/2199
BUG: KASAN: slab-out-of-bounds in snp_begin_psc+0x468/0x890
Write of size 8 at addr ffff888351566648 by task qemu-system-x86/2199
The buggy address belongs to the object at ffff888XXXXXXXXX
which belongs to the cache kmalloc-cg-32 of size 32
The buggy address is located N bytes to the right of
allocated 32-byte region [ffff888XXXXXXXXX, ffff888XXXXXXXXX)
Breakdown:
62 slab-out-of-bounds (reads + writes past allocation)
7 slab-use-after-free
4 use-after-free
All credit to Stan for the wonderful description and reproducer!
[sean: write changelog]
CVSS Score
8.8
EPSS Score
0.002
Published
2026-07-04
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Fix shadow paging use-after-free due to unexpected role
Commit 0cb2af2ea66ad ("KVM: x86: Fix shadow paging use-after-free due
to unexpected GFN") fixed a shadow paging mismatch between stored and
computed GFNs; the bug could be triggered by changing a PDE mapping from
outside the guest, and then deleting a memslot. The rmap_remove()
call would miss entries created after the PDE change because the GFN
of the leaf SPTE does not match the GFN of the struct kvm_mmu_page.
A similar hole however remains if the modified PDE points to a non-leaf
page. In this case the gfn can be made to match, but the role does not
match: the original large 2MB page creates a kvm_mmu_page with direct=1,
while the new 4KB needs a kvm_mmu_page with direct=0. However,
kvm_mmu_get_child_sp() does not compare the role, and therefore reuses
the page.
The next step is installing a leaf (4KB) SPTE on the new path which
records an rmap entry under the gfn resolved by the walk. But when
that child is zapped its parent kvm_mmu_page has direct=1 and
kvm_mmu_page_get_gfn() computes the gfn for the 4KB page as
sp->gfn + index instead of using sp->shadowed_translation[] (or sp->gfns[]
in older kernels). It therefore fails to remove the recorded entry.
When the memslot is dropped the shadow page is freed but the rmap
entry survives, as in the scenario that was already fixed. Code that
later walks that gfn (dirty logging, MMU notifier invalidation, and
so on) dereferences an sptep that lies in the freed page, causing the
use-after-free.
CVSS Score
8.8
EPSS Score
0.009
Published
2026-07-04
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del()
bt_accept_dequeue() unlinks a not-yet-accepted child from the parent
accept queue and release_sock()s it before returning, so the returned
sk has no caller reference and is unlocked.
l2cap_sock_cleanup_listen() walks these children on listening-socket
close. A concurrent HCI disconnect drives hci_rx_work ->
l2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and
frees the child sk and its l2cap_chan; cleanup_listen() then uses both:
BUG: KASAN: slab-use-after-free in l2cap_sock_kill
l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close
Freed by: l2cap_conn_del -> l2cap_sock_close_cb -> l2cap_sock_kill
This is distinct from the two fixes already in this area: commit
e83f5e24da741 ("Bluetooth: serialize accept_q access") serialises the
accept_q list/poll and takes temporary refs inside bt_accept_dequeue(),
and CVE-2025-39860 serialises the userspace close()/accept() race by
calling cleanup_listen() under lock_sock() in l2cap_sock_release().
Neither covers l2cap_conn_del() running from hci_rx_work, so this UAF
still reproduces on current bluetooth/master.
Take the reference at the source: bt_accept_dequeue() does sock_hold()
while sk is still locked, before release_sock(); callers sock_put().
cleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under
a brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops
it before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on
SOCK_DEAD. conn->lock is not taken here: cleanup_listen() runs under
the parent sk lock and that would invert
conn->lock -> chan->lock -> sk_lock (lockdep).
KASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced
12 use-after-free reports per run before this change; 0, and no lockdep
report, over 1600+ raced iterations after it on bluetooth/master.
CVSS Score
8.0
EPSS Score
0.003
Published
2026-07-02
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: use chan timer to close channels in cleanup_listen()
l2cap_chan_close() removes the channel from conn->chan_l, which
must be done under conn->lock. cleanup_listen() runs under the
parent sk_lock, so acquiring conn->lock would invert the
established conn->lock -> chan->lock -> sk_lock order.
Instead of calling l2cap_chan_close() directly, schedule
l2cap_chan_timeout with delay 0 to close the channel
asynchronously. The timeout handler already acquires conn->lock
and chan->lock in the correct order.
The timer is only armed when chan->conn is still set: if it is
already NULL, l2cap_conn_del() has already processed this channel
(l2cap_chan_del + l2cap_sock_teardown_cb + l2cap_sock_close_cb),
so there is nothing left to do. If l2cap_conn_del() races in
after the timer is armed, __clear_chan_timer() inside
l2cap_chan_del() cancels it; if the timer has already fired, the
handler returns harmlessly because chan->conn was cleared.
CVSS Score
8.8
EPSS Score
0.002
Published
2026-07-02