CVE-2026-43407
Published: May 8, 2026· Updated: May 12, 2026
Official Description
In the Linux kernel, the following vulnerability has been resolved:
libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply()
This patch fixes an out-of-bounds access in ceph_handle_auth_reply()
that can be triggered by a message of type CEPH_MSG_AUTH_REPLY. In
ceph_handle_auth_reply(), the value of the payload_len field of such a
message is stored in a variable of type int. A value greater than
INT_MAX leads to an integer overflow and is interpreted as a negative
value. This leads to decrementing the pointer address by this value and
subsequently accessing it because ceph_decode_need() only checks that
the memory access does not exceed the end address of the allocation.
This patch fixes the issue by changing the data type of payload_len to
u32. Additionally, the data type of result_msg_len is changed to u32,
as it is also a variable holding a non-negative length.
Also, an additional layer of sanity checks is introduced, ensuring that
directly after reading it from the message, payload_len and
result_msg_len are not greater than the overall segment length.
BUG: KASAN: slab-out-of-bounds in ceph_handle_auth_reply+0x642/0x7a0 [libceph]
Read of size 4 at addr ffff88811404df14 by task kworker/20:1/262
CPU: 20 UID: 0 PID: 262 Comm: kworker/20:1 Not tainted 6.19.2 #5 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: ceph-msgr ceph_con_workfn [libceph]
Call Trace:
<TASK>
dump_stack_lvl+0x76/0xa0
print_report+0xd1/0x620
? __pfx__raw_spin_lock_irqsave+0x10/0x10
? kasan_complete_mode_report_info+0x72/0x210
kasan_report+0xe7/0x130
? ceph_handle_auth_reply+0x642/0x7a0 [libceph]
? ceph_handle_auth_reply+0x642/0x7a0 [libceph]
__asan_report_load_n_noabort+0xf/0x20
ceph_handle_auth_reply+0x642/0x7a0 [libceph]
mon_dispatch+0x973/0x23d0 [libceph]
? apparmor_socket_recvmsg+0x6b/0xa0
? __pfx_mon_dispatch+0x10/0x10 [libceph]
? __kasan_check_write+0x14/0x30i
? mutex_unlock+0x7f/0xd0
? __pfx_mutex_unlock+0x10/0x10
? __pfx_do_recvmsg+0x10/0x10 [libceph]
ceph_con_process_message+0x1f1/0x650 [libceph]
process_message+0x1e/0x450 [libceph]
ceph_con_v2_try_read+0x2e48/0x6c80 [libceph]
? __pfx_ceph_con_v2_try_read+0x10/0x10 [libceph]
? save_fpregs_to_fpstate+0xb0/0x230
? raw_spin_rq_unlock+0x17/0xa0
? finish_task_switch.isra.0+0x13b/0x760
? __switch_to+0x385/0xda0
? __kasan_check_write+0x14/0x30
? mutex_lock+0x8d/0xe0
? __pfx_mutex_lock+0x10/0x10
ceph_con_workfn+0x248/0x10c0 [libceph]
process_one_work+0x629/0xf80
? __kasan_check_write+0x14/0x30
worker_thread+0x87f/0x1570
? __pfx__raw_spin_lock_irqsave+0x10/0x10
? __pfx_try_to_wake_up+0x10/0x10
? kasan_print_address_stack_frame+0x1f7/0x280
? __pfx_worker_thread+0x10/0x10
kthread+0x396/0x830
? __pfx__raw_spin_lock_irq+0x10/0x10
? __pfx_kthread+0x10/0x10
? __kasan_check_write+0x14/0x30
? recalc_sigpending+0x180/0x210
? __pfx_kthread+0x10/0x10
ret_from_fork+0x3f7/0x610
? __pfx_ret_from_fork+0x10/0x10
? __switch_to+0x385/0xda0
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
[ idryomov: replace if statements with ceph_decode_need() for
payload_len and result_msg_len ]
Technical Analysis
CVE-2026-43407 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), availability disruption (denial of service), with a CVSS base score of 9.1.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
All References (8)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-43407 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts