CVE-2026-23385

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: clone set on flush only Syzbot with fault injection triggered a failing memory allocation with GFP_KERNEL which results in a WARN splat: iter.err WARNING: net/netfilter/nf_tables_api.c:845 at nft_map_deactivate+0x34e/0x3c0 net/netfilter/nf_tables_api.c:845, CPU#0: syz.0.17/5992 Modules linked in: CPU: 0 UID: 0 PID: 5992 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:nft_map_deactivate+0x34e/0x3c0 net/netfilter/nf_tables_api.c:845 Code: 8b 05 86 5a 4e 09 48 3b 84 24 a0 00 00 00 75 62 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 63 6d fa f7 90 <0f> 0b 90 43 +80 7c 35 00 00 0f 85 23 fe ff ff e9 26 fe ff ff 89 d9 RSP: 0018:ffffc900045af780 EFLAGS: 00010293 RAX: ffffffff89ca45bd RBX: 00000000fffffff4 RCX: ffff888028111e40 RDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000 RBP: ffffc900045af870 R08: 0000000000400dc0 R09: 00000000ffffffff R10: dffffc0000000000 R11: fffffbfff1d141db R12: ffffc900045af7e0 R13: 1ffff920008b5f24 R14: dffffc0000000000 R15: ffffc900045af920 FS: 000055557a6a5500(0000) GS:ffff888125496000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb5ea271fc0 CR3: 000000003269e000 CR4: 00000000003526f0 Call Trace: <TASK> __nft_release_table+0xceb/0x11f0 net/netfilter/nf_tables_api.c:12115 nft_rcv_nl_event+0xc25/0xdb0 net/netfilter/nf_tables_api.c:12187 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85 blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380 netlink_release+0x123b/0x1ad0 net/netlink/af_netlink.c:761 __sock_release net/socket.c:662 [inline] sock_close+0xc3/0x240 net/socket.c:1455 Restrict set clone to the flush set command in the preparation phase. Add NFT_ITER_UPDATE_CLONE and use it for this purpose, update the rbtree and pipapo backends to only clone the set when this iteration type is used. As for the existing NFT_ITER_UPDATE type, update the pipapo backend to use the existing set clone if available, otherwise use the existing set representation. After this update, there is no need to clone a set that is being deleted, this includes bound anonymous set. An alternative approach to NFT_ITER_UPDATE_CLONE is to add a .clone interface and call it from the flush set path.

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

cpe:2.3:o:linux:linux_kernel:6.10:-:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* - VULNERABLE

Linux Kernel (Versions prior to commit 9154945a6394029822bd08c24cef5a3f86d0424a)

Linux Kernel (Versions prior to commit b7f67282ca2be14b727dd698b50e10cf5d8c66f9)

Linux Kernel (Versions prior to commit fb7fb4016300ac622c964069e286dc83166a5d52)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-23385
 * This is a conceptual PoC demonstrating the trigger path.
 * It requires libmnl and libnftnl to interact with netfilter.
 * The actual crash requires memory pressure/fault injection.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/netfilter/nf_tables.h>

// Conceptual representation of the netlink message to flush a set
// In a real scenario, this would use libnftnl to construct the batch.

void trigger_flush() {
    // 1. Create a netfilter table and set (conceptual)
    printf("[+] Creating nftables table and set...\n");
    // system("nft add table ip test_table");
    // system("nft add set ip test_table test_set { type ipv4_addr; }");

    // 2. Fill the set with elements to increase memory usage
    printf("[+] Adding elements to the set...\n");
    // for(int i=0; i<1000; i++) ...

    // 3. Trigger the flush command which hits the buggy code path
    printf("[!] Triggering set flush operation...\n");
    // system("nft flush set ip test_table test_set");
    
    // Note: To reliably reproduce the WARN splat, one needs to enable
    // fault injection (e.g., via debugfs) to fail the GFP_KERNEL allocation.
}

int main() {
    printf("CVE-2026-23385 PoC Runner\n");
    trigger_flush();
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-23385
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-23385
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-23385/
[4] VulDB https://vuldb.com/cve/CVE-2026-23385
[5] https://git.kernel.org/stable/c/9154945a6394029822bd08c24cef5a3f86d0424a
[6] https://git.kernel.org/stable/c/b7f67282ca2be14b727dd698b50e10cf5d8c66f9
[7] https://git.kernel.org/stable/c/fb7fb4016300ac622c964069e286dc83166a5d52

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-23385", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:38.773", "lastModified": "2026-04-24T18:44:10.210", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: clone set on flush only\n\nSyzbot with fault injection triggered a failing memory allocation with\nGFP_KERNEL which results in a WARN splat:\n\niter.err\nWARNING: net/netfilter/nf_tables_api.c:845 at nft_map_deactivate+0x34e/0x3c0 net/netfilter/nf_tables_api.c:845, CPU#0: syz.0.17/5992\nModules linked in:\nCPU: 0 UID: 0 PID: 5992 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026\nRIP: 0010:nft_map_deactivate+0x34e/0x3c0 net/netfilter/nf_tables_api.c:845\nCode: 8b 05 86 5a 4e 09 48 3b 84 24 a0 00 00 00 75 62 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 63 6d fa f7 90 <0f> 0b 90 43\n+80 7c 35 00 00 0f 85 23 fe ff ff e9 26 fe ff ff 89 d9\nRSP: 0018:ffffc900045af780 EFLAGS: 00010293\nRAX: ffffffff89ca45bd RBX: 00000000fffffff4 RCX: ffff888028111e40\nRDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000\nRBP: ffffc900045af870 R08: 0000000000400dc0 R09: 00000000ffffffff\nR10: dffffc0000000000 R11: fffffbfff1d141db R12: ffffc900045af7e0\nR13: 1ffff920008b5f24 R14: dffffc0000000000 R15: ffffc900045af920\nFS:  000055557a6a5500(0000) GS:ffff888125496000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007fb5ea271fc0 CR3: 000000003269e000 CR4: 00000000003526f0\nCall Trace:\n <TASK>\n __nft_release_table+0xceb/0x11f0 net/netfilter/nf_tables_api.c:12115\n nft_rcv_nl_event+0xc25/0xdb0 net/netfilter/nf_tables_api.c:12187\n notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85\n blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380\n netlink_release+0x123b/0x1ad0 net/netlink/af_netlink.c:761\n __sock_release net/socket.c:662 [inline]\n sock_close+0xc3/0x240 net/socket.c:1455\n\nRestrict set clone to the flush set command in the preparation phase.\nAdd NFT_ITER_UPDATE_CLONE and use it for this purpose, update the rbtree\nand pipapo backends to only clone the set when this iteration type is\nused.\n\nAs for the existing NFT_ITER_UPDATE type, update the pipapo backend to\nuse the existing set clone if available, otherwise use the existing set\nrepresentation. After this update, there is no need to clone a set that\nis being deleted, this includes bound anonymous set.\n\nAn alternative approach to NFT_ITER_UPDATE_CLONE is to add a .clone\ninterface and call it from the flush set path."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnetfilter: nf_tables: clonar conjunto solo al vaciar\n\nSyzbot con inyección de fallos activó una asignación de memoria fallida con\nGFP_KERNEL lo que resulta en un WARN splat:\n\niter.err\nADVERTENCIA: net/netfilter/nf_tables_api.c:845 en nft_map_deactivate+0x34e/0x3c0 net/netfilter/nf_tables_api.c:845, CPU#0: syz.0.17/5992\nMódulos enlazados:\nCPU: 0 UID: 0 PID: 5992 Comm: syz.0.17 No contaminado syzkaller #0 PREEMPT(full)\nNombre del hardware: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026\nRIP: 0010:nft_map_deactivate+0x34e/0x3c0 net/netfilter/nf_tables_api.c:845\nCódigo: 8b 05 86 5a 4e 09 48 3b 84 24 a0 00 00 00 75 62 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 63 6d fa f7 90 &lt;0f&gt; 0b 90 43\n+80 7c 35 00 00 0f 85 23 fe ff ff e9 26 fe ff ff 89 d9\nRSP: 0018:ffffc900045af780 EFLAGS: 00010293\nRAX: ffffffff89ca45bd RBX: 00000000fffffff4 RCX: ffff888028111e40\nRDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000\nRBP: ffffc900045af870 R08: 0000000000400dc0 R09: 00000000ffffffff\nR10: dffffc0000000000 R11: fffffbfff1d141db R12: ffffc900045af7e0\nR13: 1ffff920008b5f24 R14: dffffc0000000000 R15: ffffc900045af920\nFS:  000055557a6a5500(0000) GS:ffff888125496000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007fb5ea271fc0 CR3: 000000003269e000 CR4: 00000000003526f0\nRastro de llamada:\n \n __nft_release_table+0xceb/0x11f0 net/netfilter/nf_tables_api.c:12115\n nft_rcv_nl_event+0xc25/0xdb0 net/netfilter/nf_tables_api.c:12187\n notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85\n blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380\n netlink_release+0x123b/0x1ad0 net/netlink/af_netlink.c:761\n __sock_release net/socket.c:662 [inline]\n sock_close+0xc3/0x240 net/socket.c:1455\n\nRestringir la clonación del conjunto al comando de vaciado del conjunto en la fase de preparación.\nAñadir NFT_ITER_UPDATE_CLONE y usarlo para este propósito, actualizar los backends rbtree\ny pipapo para clonar el conjunto solo cuando se usa este tipo de iteración.\n\nEn cuanto al tipo NFT_ITER_UPDATE existente, actualizar el backend pipapo para\nusar el

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