CVE-2026-43407
Linux Kernel out-of-bounds read
- Published8 May 2026
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 ]
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/6cee34d6669fe176b4259131adb1a145c939b472
- https://git.kernel.org/stable/c/8bb87547e92dcf0928ed763c60e0ac8d733c3656
- https://git.kernel.org/stable/c/9f9e2297f45fc2d2524eb104c289d69ddef95665
- https://git.kernel.org/stable/c/b282c43ed156ae15ea76748fc15cd5c39dc9ab72
- https://git.kernel.org/stable/c/ea080b21092590122c3f971cf588932cdbf47847
- https://git.kernel.org/stable/c/ed024d2f4c79c0eb2464df0fb640610ac301f9a0
References
- https://git.kernel.org/stable/c/6cee34d6669fe176b4259131adb1a145c939b472
- https://git.kernel.org/stable/c/8bb87547e92dcf0928ed763c60e0ac8d733c3656
- https://git.kernel.org/stable/c/9f9e2297f45fc2d2524eb104c289d69ddef95665
- https://git.kernel.org/stable/c/b282c43ed156ae15ea76748fc15cd5c39dc9ab72
- https://git.kernel.org/stable/c/ea080b21092590122c3f971cf588932cdbf47847
- https://git.kernel.org/stable/c/ed024d2f4c79c0eb2464df0fb640610ac301f9a0
- https://git.kernel.org/stable/c/edc678e5cd11730a2834b43071d8923f05bc334d
- https://git.kernel.org/stable/c/f9da5c1bbac5c8e33259fe00ed7347438fffa969
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-43407 being actively exploited?
CVE-2026-43407 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.73%.
How severe is CVE-2026-43407?
CVE-2026-43407 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.73% probability of exploitation.
Which products are affected by CVE-2026-43407?
Affected products include Linux Kernel.
How do I fix CVE-2026-43407?
Upgrade affected software to a fixed version, for example Linux Kernel 5.10.253 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.