Linux: Out-of-bounds Read
CVE-2026-43407 is a critical-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions ea080b21092590122c3f971cf588932cdbf47847, edc678e5cd11730a2834b43071d8923f05bc334d, 6cee34d6669fe176b4259131adb1a145c939b472 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.66% chance of exploitation within 30 days, higher than 52% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to ea080b21092590122c3f971cf588932cdbf47847 or edc678e5cd11730a2834b43071d8923f05bc334d or 6cee34d6669fe176b4259131adb1a145c939b472 or 8bb87547e92dcf0928ed763c60e0ac8d733c3656, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.167 or 6.6.130, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc up to, but not including, ea080b21092590122c3f971cf588932cdbf47847; 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc up to, but not including, edc678e5cd11730a2834b43071d8923f05bc334d; 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc up to, but not including, 6cee34d6669fe176b4259131adb1a145c939b472; 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc up to, but not including, 8bb87547e92dcf0928ed763c60e0ac8d733c3656; 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc up to, but not including, ed024d2f4c79c0eb2464df0fb640610ac301f9a0; 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc up to, but not including, f9da5c1bbac5c8e33259fe00ed7347438fffa969; 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc up to, but not including, 9f9e2297f45fc2d2524eb104c289d69ddef95665; 4e7a5dcd1bbab6560fbc8ada29a840e7a20ed7bc up to, but not including, b282c43ed156ae15ea76748fc15cd5c39dc9ab72; and 1 more ranges | ea080b21092590122c3f971cf588932cdbf47847, edc678e5cd11730a2834b43071d8923f05bc334d, 6cee34d6669fe176b4259131adb1a145c939b472, 8bb87547e92dcf0928ed763c60e0ac8d733c3656, ed024d2f4c79c0eb2464df0fb640610ac301f9a0, f9da5c1bbac5c8e33259fe00ed7347438fffa969 |
| Linux | Linux Kernel | 2.6.34.1 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.167; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.78; 6.13 up to, but not including, 6.18.19; 6.19 up to, but not including, 6.19.9; 2.6.34; and 1 more ranges | 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.19 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.
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 ]
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/6cee34d6669fe176b4259131adb1a145c939b472
- git.kernel.org/stable/c/8bb87547e92dcf0928ed763c60e0ac8d733c3656
- git.kernel.org/stable/c/9f9e2297f45fc2d2524eb104c289d69ddef95665
- git.kernel.org/stable/c/b282c43ed156ae15ea76748fc15cd5c39dc9ab72
- git.kernel.org/stable/c/ea080b21092590122c3f971cf588932cdbf47847
- git.kernel.org/stable/c/ed024d2f4c79c0eb2464df0fb640610ac301f9a0
- git.kernel.org/stable/c/edc678e5cd11730a2834b43071d8923f05bc334d
- git.kernel.org/stable/c/f9da5c1bbac5c8e33259fe00ed7347438fffa969
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 8.2 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 9.1 Critical severity
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