Linux: >> Linux Kernel >> 2.6.25.16 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
Oskar Kjos reported the following problem.
ip4ip6_err() calls icmp_send() on a cloned skb whose cb[] was written
by the IPv6 receive path as struct inet6_skb_parm. icmp_send() passes
IPCB(skb2) to __ip_options_echo(), which interprets that cb[] region
as struct inet_skb_parm (IPv4). The layouts differ: inet6_skb_parm.nhoff
at offset 14 overlaps inet_skb_parm.opt.rr, producing a non-zero rr
value. __ip_options_echo() then reads optlen from attacker-controlled
packet data at sptr[rr+1] and copies that many bytes into dopt->__data,
a fixed 40-byte stack buffer (IP_OPTIONS_DATA_FIXED_SIZE).
To fix this we clear skb2->cb[], as suggested by Oskar Kjos.
Also add minimal IPv4 header validation (version == 4, ihl >= 5).
CVSS Score
9.8
EPSS Score
0.006
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
net/x25: Fix potential double free of skb
When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at
line 48 and returns 1 (error).
This error propagates back through the call chain:
x25_queue_rx_frame returns 1
|
v
x25_state3_machine receives the return value 1 and takes the else
branch at line 278, setting queued=0 and returning 0
|
v
x25_process_rx_frame returns queued=0
|
v
x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb)
again
This would free the same skb twice. Looking at x25_backlog_rcv:
net/x25/x25_in.c:x25_backlog_rcv() {
...
queued = x25_process_rx_frame(sk, skb);
...
if (!queued)
kfree_skb(skb);
}
CVSS Score
9.8
EPSS Score
0.005
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
gpio: omap: do not register driver in probe()
Commit 11a78b794496 ("ARM: OMAP: MPUIO wake updates") registers the
omap_mpuio_driver from omap_mpuio_init(), which is called from
omap_gpio_probe().
However, it neither makes sense to register drivers from probe()
callbacks of other drivers, nor does the driver core allow registering
drivers with a device lock already being held.
The latter was revealed by commit dc23806a7c47 ("driver core: enforce
device_lock for driver_match_device()") leading to a potential deadlock
condition described in [1].
Additionally, the omap_mpuio_driver is never unregistered from the
driver core, even if the module is unloaded.
Hence, register the omap_mpuio_driver from the module initcall and
unregister it in module_exit().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-27
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ip6t_eui64: reject invalid MAC header for all packets
`eui64_mt6()` derives a modified EUI-64 from the Ethernet source address
and compares it with the low 64 bits of the IPv6 source address.
The existing guard only rejects an invalid MAC header when
`par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()`
can still reach `eth_hdr(skb)` even when the MAC header is not valid.
Fix this by removing the `par->fragoff != 0` condition so that packets
with an invalid MAC header are rejected before accessing `eth_hdr(skb)`.
CVSS Score
9.4
EPSS Score
0.003
Published
2026-04-25
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_netem: fix out-of-bounds access in packet corruption
In netem_enqueue(), the packet corruption logic uses
get_random_u32_below(skb_headlen(skb)) to select an index for
modifying skb->data. When an AF_PACKET TX_RING sends fully non-linear
packets over an IPIP tunnel, skb_headlen(skb) evaluates to 0.
Passing 0 to get_random_u32_below() takes the variable-ceil slow path
which returns an unconstrained 32-bit random integer. Using this
unconstrained value as an offset into skb->data results in an
out-of-bounds memory access.
Fix this by verifying skb_headlen(skb) is non-zero before attempting
to corrupt the linear data area. Fully non-linear packets will silently
bypass the corruption logic.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-04-25
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: only handle RESPONSE during service challenge
Only process RESPONSE packets while the service connection is still in
RXRPC_CONN_SERVICE_CHALLENGING. Check that state under state_lock before
running response verification and security initialization, then use a local
secured flag to decide whether to queue the secured-connection work after
the state transition. This keeps duplicate or late RESPONSE packets from
re-running the setup path and removes the unlocked post-transition state
test.
CVSS Score
7.5
EPSS Score
0.004
Published
2026-04-25
In the Linux kernel, the following vulnerability has been resolved:
netfilter: xt_multiport: validate range encoding in checkentry
ports_match_v1() treats any non-zero pflags entry as the start of a
port range and unconditionally consumes the next ports[] element as
the range end.
The checkentry path currently validates protocol, flags and count, but
it does not validate the range encoding itself. As a result, malformed
rules can mark the last slot as a range start or place two range starts
back to back, leaving ports_match_v1() to step past the last valid
ports[] element while interpreting the rule.
Reject malformed multiport v1 rules in checkentry by validating that
each range start has a following element and that the following element
is not itself marked as another range start.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-25
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ip6t_rt: reject oversized addrnr in rt_mt6_check()
Reject rt match rules whose addrnr exceeds IP6T_RT_HOPS.
rt_mt6() expects addrnr to stay within the bounds of rtinfo->addrs[].
Validate addrnr during rule installation so malformed rules are rejected
before the match logic can use an out-of-range value.
CVSS Score
7.1
EPSS Score
0.001
Published
2026-04-25
In the Linux kernel, the following vulnerability has been resolved:
xfrm: clear trailing padding in build_polexpire()
build_expire() clears the trailing padding bytes of struct
xfrm_user_expire after setting the hard field via memset_after(),
but the analogous function build_polexpire() does not do this for
struct xfrm_user_polexpire.
The padding bytes after the __u8 hard field are left
uninitialized from the heap allocation, and are then sent to
userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners,
leaking kernel heap memory contents.
Add the missing memset_after() call, matching build_expire().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-04-24
In the Linux kernel, the following vulnerability has been resolved:
Input: uinput - fix circular locking dependency with ff-core
A lockdep circular locking dependency warning can be triggered
reproducibly when using a force-feedback gamepad with uinput (for
example, playing ELDEN RING under Wine with a Flydigi Vader 5
controller):
ff->mutex -> udev->mutex -> input_mutex -> dev->mutex -> ff->mutex
The cycle is caused by four lock acquisition paths:
1. ff upload: input_ff_upload() holds ff->mutex and calls
uinput_dev_upload_effect() -> uinput_request_submit() ->
uinput_request_send(), which acquires udev->mutex.
2. device create: uinput_ioctl_handler() holds udev->mutex and calls
uinput_create_device() -> input_register_device(), which acquires
input_mutex.
3. device register: input_register_device() holds input_mutex and
calls kbd_connect() -> input_register_handle(), which acquires
dev->mutex.
4. evdev release: evdev_release() calls input_flush_device() under
dev->mutex, which calls input_ff_flush() acquiring ff->mutex.
Fix this by introducing a new state_lock spinlock to protect
udev->state and udev->dev access in uinput_request_send() instead of
acquiring udev->mutex. The function only needs to atomically check
device state and queue an input event into the ring buffer via
uinput_dev_event() -- both operations are safe under a spinlock
(ktime_get_ts64() and wake_up_interruptible() do not sleep). This
breaks the ff->mutex -> udev->mutex link since a spinlock is a leaf in
the lock ordering and cannot form cycles with mutexes.
To keep state transitions visible to uinput_request_send(), protect
writes to udev->state in uinput_create_device() and
uinput_destroy_device() with the same state_lock spinlock.
Additionally, move init_completion(&request->done) from
uinput_request_send() to uinput_request_submit() before
uinput_request_reserve_slot(). Once the slot is allocated,
uinput_flush_requests() may call complete() on it at any time from
the destroy path, so the completion must be initialised before the
request becomes visible.
Lock ordering after the fix:
ff->mutex -> state_lock (spinlock, leaf)
udev->mutex -> state_lock (spinlock, leaf)
udev->mutex -> input_mutex -> dev->mutex -> ff->mutex (no back-edge)
CVSS Score
7.8
EPSS Score
0.001
Published
2026-04-24