Linux: >> Linux Kernel >> 5.15.117 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
nexthop: fix IPv6 route referencing IPv4 nexthop
syzbot reported a panic [1] [2].
When an IPv6 nexthop is replaced with an IPv4 nexthop, the has_v4 flag
of all groups containing this nexthop is not updated. This is because
nh_group_v4_update is only called when replacing AF_INET to AF_INET6,
but the reverse direction (AF_INET6 to AF_INET) is missed.
This allows a stale has_v4=false to bypass fib6_check_nexthop, causing
IPv6 routes to be attached to groups that effectively contain only AF_INET
members. Subsequent route lookups then call nexthop_fib6_nh() which
returns NULL for the AF_INET member, leading to a NULL pointer
dereference.
Fix by calling nh_group_v4_update whenever the family changes, not just
AF_INET to AF_INET6.
Reproducer:
# AF_INET6 blackhole
ip -6 nexthop add id 1 blackhole
# group with has_v4=false
ip nexthop add id 100 group 1
# replace with AF_INET (no -6), has_v4 stays false
ip nexthop replace id 1 blackhole
# pass stale has_v4 check
ip -6 route add 2001:db8::/64 nhid 100
# panic
ping -6 2001:db8::1
[1] https://syzkaller.appspot.com/bug?id=e17283eb2f8dcf3dd9b47fe6f67a95f71faadad0
[2] https://syzkaller.appspot.com/bug?id=8699b6ae54c9f35837d925686208402949e12ef3
CVSS Score
5.5
EPSS Score
0.002
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nat: use kfree_rcu to release ops
Florian Westphal says:
"Historically this is not an issue, even for normal base hooks: the data
path doesn't use the original nf_hook_ops that are used to register the
callbacks.
However, in v5.14 I added the ability to dump the active netfilter
hooks from userspace.
This code will peek back into the nf_hook_ops that are available
at the tail of the pointer-array blob used by the datapath.
The nat hooks are special, because they are called indirectly from
the central nat dispatcher hook. They are currently invisible to
the nfnl hook dump subsystem though.
But once that changes the nat ops structures have to be deferred too."
Update nf_nat_register_fn() to deal with partial exposition of the hooks
from error path which can be also an issue for nfnetlink_hook.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
netfilter: xtables: restrict several matches to inet family
This is a partial revert of:
commit ab4f21e6fb1c ("netfilter: xtables: use NFPROTO_UNSPEC in more extensions")
to allow ipv4 and ipv6 only.
- xt_mac
- xt_owner
- xt_physdev
These extensions are not used by ebtables in userspace.
Moreover, xt_realm is only for ipv4, since dst->tclassid is ipv4
specific.
CVSS Score
5.5
EPSS Score
0.002
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
netfilter: conntrack: remove sprintf usage
Replace it with scnprintf, the buffer sizes are expected to be large enough
to hold the result, no need for snprintf+overflow check.
Increase buffer size in mangle_content_len() while at it.
BUG: KASAN: stack-out-of-bounds in vsnprintf+0xea5/0x1270
Write of size 1 at addr [..]
vsnprintf+0xea5/0x1270
sprintf+0xb1/0xe0
mangle_content_len+0x1ac/0x280
nf_nat_sdp_session+0x1cc/0x240
process_sdp+0x8f8/0xb80
process_invite_request+0x108/0x2b0
process_sip_msg+0x5da/0xf50
sip_help_tcp+0x45e/0x780
nf_confirm+0x34d/0x990
[..]
CVSS Score
9.8
EPSS Score
0.004
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
pppoe: drop PFC frames
RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT
RECOMMENDED for PPPoE. In practice, pppd does not support negotiating
PFC for PPPoE sessions, and the current PPPoE driver assumes an
uncompressed (2-byte) protocol field. However, the generic PPP layer
function ppp_input() is not aware of the negotiation result, and still
accepts PFC frames.
If a peer with a broken implementation or an attacker sends a frame with
a compressed (1-byte) protocol field, the subsequent PPP payload is
shifted by one byte. This causes the network header to be 4-byte
misaligned, which may trigger unaligned access exceptions on some
architectures.
To reduce the attack surface, drop PPPoE PFC frames. Introduce
ppp_skb_is_compressed_proto() helper function to be used in both
ppp_generic.c and pppoe.c to avoid open-coding.
CVSS Score
7.5
EPSS Score
0.005
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
sctp: fix OOB write to userspace in sctp_getsockopt_peer_auth_chunks
sctp_getsockopt_peer_auth_chunks() checks that the caller's optval
buffer is large enough for the peer AUTH chunk list with
if (len < num_chunks)
return -EINVAL;
but then writes num_chunks bytes to p->gauth_chunks, which lives
at offset offsetof(struct sctp_authchunks, gauth_chunks) == 8
inside optval. The check is missing the sizeof(struct
sctp_authchunks) = 8-byte header. When the caller supplies
len == num_chunks (for any num_chunks > 0) the test passes but
copy_to_user() writes sizeof(struct sctp_authchunks) = 8 bytes
past the declared buffer.
The sibling function sctp_getsockopt_local_auth_chunks() at the
next line already has the correct check:
if (len < sizeof(struct sctp_authchunks) + num_chunks)
return -EINVAL;
Align the peer variant with its sibling.
Reproducer confirms on v7.0-13-generic: an unprivileged userspace
caller that opens a loopback SCTP association with AUTH enabled,
queries num_chunks with a short optval, then issues the real
getsockopt with len == num_chunks and sentinel bytes painted past
the buffer observes those sentinel bytes overwritten with the
peer's AUTH chunk type. The bytes written are under the peer's
control but land in the caller's own userspace; this is not a
kernel memory corruption, but it is a kernel-side contract
violation that can silently corrupt adjacent userspace data.
CVSS Score
7.8
EPSS Score
0.002
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
af_unix: Drop all SCM attributes for SOCKMAP.
SOCKMAP can hide inflight fd from AF_UNIX GC.
When a socket in SOCKMAP receives skb with inflight fd,
sk_psock_verdict_data_ready() looks up the mapped socket and
enqueue skb to its psock->ingress_skb.
Since neither the old nor the new GC can inspect the psock
queue, the hidden skb leaks the inflight sockets. Note that
this cannot be detected via kmemleak because inflight sockets
are linked to a global list.
In addition, SOCKMAP redirect breaks the Tarjan-based GC's
assumption that unix_edge.successor is always alive, which
is no longer true once skb is redirected, resulting in
use-after-free below. [0]
Moreover, SOCKMAP does not call scm_stat_del() properly,
so unix_show_fdinfo() could report an incorrect fd count.
sk_msg_recvmsg() does not support any SCM attributes in the
first place.
Let's drop all SCM attributes before passing skb to the
SOCKMAP layer.
[0]:
BUG: KASAN: slab-use-after-free in unix_del_edges (net/unix/garbage.c:118 net/unix/garbage.c:181 net/unix/garbage.c:251)
Read of size 8 at addr ffff888125362670 by task kworker/56:1/496
CPU: 56 UID: 0 PID: 496 Comm: kworker/56:1 Not tainted 7.0.0-rc7-00263-gb9d8b856689d #3 PREEMPT(lazy)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
Workqueue: events sk_psock_backlog
Call Trace:
<TASK>
dump_stack_lvl (lib/dump_stack.c:122)
print_report (mm/kasan/report.c:379)
kasan_report (mm/kasan/report.c:597)
unix_del_edges (net/unix/garbage.c:118 net/unix/garbage.c:181 net/unix/garbage.c:251)
unix_destroy_fpl (net/unix/garbage.c:317)
unix_destruct_scm (./include/net/scm.h:80 ./include/net/scm.h:86 net/unix/af_unix.c:1976)
sk_psock_backlog (./include/linux/skbuff.h:?)
process_scheduled_works (kernel/workqueue.c:?)
worker_thread (kernel/workqueue.c:?)
kthread (kernel/kthread.c:438)
ret_from_fork (arch/x86/kernel/process.c:164)
ret_from_fork_asm (arch/x86/entry/entry_64.S:258)
</TASK>
Allocated by task 955:
kasan_save_track (mm/kasan/common.c:58 mm/kasan/common.c:78)
__kasan_slab_alloc (mm/kasan/common.c:369)
kmem_cache_alloc_noprof (mm/slub.c:4539)
sk_prot_alloc (net/core/sock.c:2240)
sk_alloc (net/core/sock.c:2301)
unix_create1 (net/unix/af_unix.c:1099)
unix_create (net/unix/af_unix.c:1169)
__sock_create (net/socket.c:1606)
__sys_socketpair (net/socket.c:1811)
__x64_sys_socketpair (net/socket.c:1863 net/socket.c:1860 net/socket.c:1860)
do_syscall_64 (arch/x86/entry/syscall_64.c:?)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
Freed by task 496:
kasan_save_track (mm/kasan/common.c:58 mm/kasan/common.c:78)
kasan_save_free_info (mm/kasan/generic.c:587)
__kasan_slab_free (mm/kasan/common.c:287)
kmem_cache_free (mm/slub.c:6165)
__sk_destruct (net/core/sock.c:2282 net/core/sock.c:2384)
sk_psock_destroy (./include/net/sock.h:?)
process_scheduled_works (kernel/workqueue.c:?)
worker_thread (kernel/workqueue.c:?)
kthread (kernel/kthread.c:438)
ret_from_fork (arch/x86/kernel/process.c:164)
ret_from_fork_asm (arch/x86/entry/entry_64.S:258)
CVSS Score
7.8
EPSS Score
0.001
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
ipv6: fix possible UAF in icmpv6_rcv()
Caching saddr and daddr before pskb_pull() is problematic
since skb->head can change.
Remove these temporary variables:
- We only access &ipv6_hdr(skb)->saddr and &ipv6_hdr(skb)->daddr
when net_dbg_ratelimited() is called in the slow path.
- Avoid potential future misuse after pskb_pull() call.
CVSS Score
9.8
EPSS Score
0.004
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
fs/adfs: validate nzones in adfs_validate_bblk()
Reject ADFS disc records with a zero zone count during boot block
validation, before the disc record is used.
When nzones is 0, adfs_read_map() passes it to kmalloc_array(0, ...)
which returns ZERO_SIZE_PTR, and adfs_map_layout() then writes to
dm[-1], causing an out-of-bounds write before the allocated buffer.
adfs_validate_dr0() already rejects nzones != 1 for old-format
images. Add the equivalent check to adfs_validate_bblk() for
new-format images so that a crafted image with nzones == 0 is
rejected at probe time.
Found by syzkaller.
CVSS Score
7.8
EPSS Score
0.002
Published
2026-06-24
In the Linux kernel, the following vulnerability has been resolved:
tipc: fix double-free in tipc_buf_append()
tipc_msg_validate() can potentially reallocate the skb it is validating,
freeing the old one. In tipc_buf_append(), it was being called with a
pointer to a local variable which was a copy of the caller's skb
pointer.
If the skb was reallocated and validation subsequently failed, the error
handling path would free the original skb pointer, which had already
been freed, leading to double-free.
Fix this by checking if head now points to a newly allocated reassembled
skb. If it does, reassign *headbuf for later freeing operations.
CVSS Score
9.8
EPSS Score
0.004
Published
2026-06-24