Linux: >> Linux Kernel >> 4.4.292 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: SCO: Fix use-after-free in sco_recv_frame() due to missing sock_hold
sco_recv_frame() reads conn->sk under sco_conn_lock() but immediately
releases the lock without holding a reference to the socket. A concurrent
close() can free the socket between the lock release and the subsequent
sk->sk_state access, resulting in a use-after-free.
Other functions in the same file (sco_sock_timeout(), sco_conn_del())
correctly use sco_sock_hold() to safely hold a reference under the lock.
Fix by using sco_sock_hold() to take a reference before releasing the
lock, and adding sock_put() on all exit paths.
CVSS Score
8.8
EPSS Score
0.0
Published
2026-04-06
In the Linux kernel, the following vulnerability has been resolved:
nfsd: fix heap overflow in NFSv4.0 LOCK replay cache
The NFSv4.0 replay cache uses a fixed 112-byte inline buffer
(rp_ibuf[NFSD4_REPLAY_ISIZE]) to store encoded operation responses.
This size was calculated based on OPEN responses and does not account
for LOCK denied responses, which include the conflicting lock owner as
a variable-length field up to 1024 bytes (NFS4_OPAQUE_LIMIT).
When a LOCK operation is denied due to a conflict with an existing lock
that has a large owner, nfsd4_encode_operation() copies the full encoded
response into the undersized replay buffer via read_bytes_from_xdr_buf()
with no bounds check. This results in a slab-out-of-bounds write of up
to 944 bytes past the end of the buffer, corrupting adjacent heap memory.
This can be triggered remotely by an unauthenticated attacker with two
cooperating NFSv4.0 clients: one sets a lock with a large owner string,
then the other requests a conflicting lock to provoke the denial.
We could fix this by increasing NFSD4_REPLAY_ISIZE to allow for a full
opaque, but that would increase the size of every stateowner, when most
lockowners are not that large.
Instead, fix this by checking the encoded response length against
NFSD4_REPLAY_ISIZE before copying into the replay buffer. If the
response is too large, set rp_buflen to 0 to skip caching the replay
payload. The status is still cached, and the client already received the
correct response on the original request.
CVSS Score
9.8
EPSS Score
0.002
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd
The /proc/fs/nfs/exports proc entry is created at module init
and persists for the module's lifetime. exports_proc_open()
captures the caller's current network namespace and stores
its svc_export_cache in seq->private, but takes no reference
on the namespace. If the namespace is subsequently torn down
(e.g. container destruction after the opener does setns() to a
different namespace), nfsd_net_exit() calls nfsd_export_shutdown()
which frees the cache. Subsequent reads on the still-open fd
dereference the freed cache_detail, walking a freed hash table.
Hold a reference on the struct net for the lifetime of the open
file descriptor. This prevents nfsd_net_exit() from running --
and thus prevents nfsd_export_shutdown() from freeing the cache
-- while any exports fd is open. cache_detail already stores
its net pointer (cd->net, set by cache_create_net()), so
exports_release() can retrieve it without additional per-file
storage.
CVSS Score
7.8
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
nvdimm/bus: Fix potential use after free in asynchronous initialization
Dingisoul with KASAN reports a use after free if device_add() fails in
nd_async_device_register().
Commit b6eae0f61db2 ("libnvdimm: Hold reference on parent while
scheduling async init") correctly added a reference on the parent device
to be held until asynchronous initialization was complete. However, if
device_add() results in an allocation failure the ref count of the
device drops to 0 prior to the parent pointer being accessed. Thus
resulting in use after free.
The bug bot AI correctly identified the fix. Save a reference to the
parent pointer to be used to drop the parent reference regardless of the
outcome of device_add().
CVSS Score
7.8
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
sunrpc: fix cache_request leak in cache_release
When a reader's file descriptor is closed while in the middle of reading
a cache_request (rp->offset != 0), cache_release() decrements the
request's readers count but never checks whether it should free the
request.
In cache_read(), when readers drops to 0 and CACHE_PENDING is clear, the
cache_request is removed from the queue and freed along with its buffer
and cache_head reference. cache_release() lacks this cleanup.
The only other path that frees requests with readers == 0 is
cache_dequeue(), but it runs only when CACHE_PENDING transitions from
set to clear. If that transition already happened while readers was
still non-zero, cache_dequeue() will have skipped the request, and no
subsequent call will clean it up.
Add the same cleanup logic from cache_read() to cache_release(): after
decrementing readers, check if it reached 0 with CACHE_PENDING clear,
and if so, dequeue and free the cache_request.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix krb5 mount with username option
Customer reported that some of their krb5 mounts were failing against
a single server as the client was trying to mount the shares with
wrong credentials. It turned out the client was reusing SMB session
from first mount to try mounting the other shares, even though a
different username= option had been specified to the other mounts.
By using username mount option along with sec=krb5 to search for
principals from keytab is supported by cifs.upcall(8) since
cifs-utils-4.8. So fix this by matching username mount option in
match_session() even with Kerberos.
For example, the second mount below should fail with -ENOKEY as there
is no 'foobar' principal in keytab (/etc/krb5.keytab). The client
ends up reusing SMB session from first mount to perform the second
one, which is wrong.
```
$ ktutil
ktutil: add_entry -password -p testuser -k 1 -e aes256-cts
Password for testuser@ZELDA.TEST:
ktutil: write_kt /etc/krb5.keytab
ktutil: quit
$ klist -ke
Keytab name: FILE:/etc/krb5.keytab
KVNO Principal
---- ----------------------------------------------------------------
1 testuser@ZELDA.TEST (aes256-cts-hmac-sha1-96)
$ mount.cifs //w22-root2/scratch /mnt/1 -o sec=krb5,username=testuser
$ mount.cifs //w22-root2/scratch /mnt/2 -o sec=krb5,username=foobar
$ mount -t cifs | grep -Po 'username=\K\w+'
testuser
testuser
```
CVSS Score
8.1
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Validate L2CAP_INFO_RSP payload length before access
l2cap_information_rsp() checks that cmd_len covers the fixed
l2cap_info_rsp header (type + result, 4 bytes) but then reads
rsp->data without verifying that the payload is present:
- L2CAP_IT_FEAT_MASK calls get_unaligned_le32(rsp->data), which reads
4 bytes past the header (needs cmd_len >= 8).
- L2CAP_IT_FIXED_CHAN reads rsp->data[0], 1 byte past the header
(needs cmd_len >= 5).
A truncated L2CAP_INFO_RSP with result == L2CAP_IR_SUCCESS triggers an
out-of-bounds read of adjacent skb data.
Guard each data access with the required payload length check. If the
payload is too short, skip the read and let the state machine complete
with safe defaults (feat_mask and remote_fixed_chan remain zero from
kzalloc), so the info timer cleanup and l2cap_conn_start() still run
and the connection is not stalled.
CVSS Score
8.1
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
mtd: Avoid boot crash in RedBoot partition table parser
Given CONFIG_FORTIFY_SOURCE=y and a recent compiler,
commit 439a1bcac648 ("fortify: Use __builtin_dynamic_object_size() when
available") produces the warning below and an oops.
Searching for RedBoot partition table in 50000000.flash at offset 0x7e0000
------------[ cut here ]------------
WARNING: lib/string_helpers.c:1035 at 0xc029e04c, CPU#0: swapper/0/1
memcmp: detected buffer overflow: 15 byte read of buffer size 14
Modules linked in:
CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.19.0 #1 NONE
As Kees said, "'names' is pointing to the final 'namelen' many bytes
of the allocation ... 'namelen' could be basically any length at all.
This fortify warning looks legit to me -- this code used to be reading
beyond the end of the allocation."
Since the size of the dynamic allocation is calculated with strlen()
we can use strcmp() instead of memcmp() and remain within bounds.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: Limit BO list entry count to prevent resource exhaustion
Userspace can pass an arbitrary number of BO list entries via the
bo_number field. Although the previous multiplication overflow check
prevents out-of-bounds allocation, a large number of entries could still
cause excessive memory allocation (up to potentially gigabytes) and
unnecessarily long list processing times.
Introduce a hard limit of 128k entries per BO list, which is more than
sufficient for any realistic use case (e.g., a single list containing all
buffers in a large scene). This prevents memory exhaustion attacks and
ensures predictable performance.
Return -EINVAL if the requested entry count exceeds the limit
(cherry picked from commit 688b87d39e0aa8135105b40dc167d74b5ada5332)
CVSS Score
5.5
EPSS Score
0.0
Published
2026-04-03
In the Linux kernel, the following vulnerability has been resolved:
serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN
uart_write_room() and uart_write() behave inconsistently when
xmit_buf is NULL (which happens for PORT_UNKNOWN ports that were
never properly initialized):
- uart_write_room() returns kfifo_avail() which can be > 0
- uart_write() checks xmit_buf and returns 0 if NULL
This inconsistency causes an infinite loop in drivers that rely on
tty_write_room() to determine if they can write:
while (tty_write_room(tty) > 0) {
written = tty->ops->write(...);
// written is always 0, loop never exits
}
For example, caif_serial's handle_tx() enters an infinite loop when
used with PORT_UNKNOWN serial ports, causing system hangs.
Fix by making uart_write_room() also check xmit_buf and return 0 if
it's NULL, consistent with uart_write().
Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13
CVSS Score
5.5
EPSS Score
0.0
Published
2026-04-03