CVE-2026-23449

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: teql: Fix double-free in teql_master_xmit Whenever a TEQL devices has a lockless Qdisc as root, qdisc_reset should be called using the seq_lock to avoid racing with the datapath. Failure to do so may cause crashes like the following: [ 238.028993][ T318] BUG: KASAN: double-free in skb_release_data (net/core/skbuff.c:1139) [ 238.029328][ T318] Free of addr ffff88810c67ec00 by task poc_teql_uaf_ke/318 [ 238.029749][ T318] [ 238.029900][ T318] CPU: 3 UID: 0 PID: 318 Comm: poc_teql_ke Not tainted 7.0.0-rc3-00149-ge5b31d988a41 #704 PREEMPT(full) [ 238.029906][ T318] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 238.029910][ T318] Call Trace: [ 238.029913][ T318] <TASK> [ 238.029916][ T318] dump_stack_lvl (lib/dump_stack.c:122) [ 238.029928][ T318] print_report (mm/kasan/report.c:379 mm/kasan/report.c:482) [ 238.029940][ T318] ? skb_release_data (net/core/skbuff.c:1139) [ 238.029944][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221) ... [ 238.029957][ T318] ? skb_release_data (net/core/skbuff.c:1139) [ 238.029969][ T318] kasan_report_invalid_free (mm/kasan/report.c:221 mm/kasan/report.c:563) [ 238.029979][ T318] ? skb_release_data (net/core/skbuff.c:1139) [ 238.029989][ T318] check_slab_allocation (mm/kasan/common.c:231) [ 238.029995][ T318] kmem_cache_free (mm/slub.c:2637 (discriminator 1) mm/slub.c:6168 (discriminator 1) mm/slub.c:6298 (discriminator 1)) [ 238.030004][ T318] skb_release_data (net/core/skbuff.c:1139) ... [ 238.030025][ T318] sk_skb_reason_drop (net/core/skbuff.c:1256) [ 238.030032][ T318] pfifo_fast_reset (./include/linux/ptr_ring.h:171 ./include/linux/ptr_ring.h:309 ./include/linux/skb_array.h:98 net/sched/sch_generic.c:827) [ 238.030039][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221) ... [ 238.030054][ T318] qdisc_reset (net/sched/sch_generic.c:1034) [ 238.030062][ T318] teql_destroy (./include/linux/spinlock.h:395 net/sched/sch_teql.c:157) [ 238.030071][ T318] __qdisc_destroy (./include/net/pkt_sched.h:328 net/sched/sch_generic.c:1077) [ 238.030077][ T318] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159) [ 238.030089][ T318] ? __pfx_qdisc_graft (net/sched/sch_api.c:1091) [ 238.030095][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221) [ 238.030102][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221) [ 238.030106][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221) [ 238.030114][ T318] tc_get_qdisc (net/sched/sch_api.c:1529 net/sched/sch_api.c:1556) ... [ 238.072958][ T318] Allocated by task 303 on cpu 5 at 238.026275s: [ 238.073392][ T318] kasan_save_stack (mm/kasan/common.c:58) [ 238.073884][ T318] kasan_save_track (mm/kasan/common.c:64 (discriminator 5) mm/kasan/common.c:79 (discriminator 5)) [ 238.074230][ T318] __kasan_slab_alloc (mm/kasan/common.c:369) [ 238.074578][ T318] kmem_cache_alloc_node_noprof (./include/linux/kasan.h:253 mm/slub.c:4542 mm/slub.c:4869 mm/slub.c:4921) [ 238.076091][ T318] kmalloc_reserve (net/core/skbuff.c:616 (discriminator 107)) [ 238.076450][ T318] __alloc_skb (net/core/skbuff.c:713) [ 238.076834][ T318] alloc_skb_with_frags (./include/linux/skbuff.h:1383 net/core/skbuff.c:6763) [ 238.077178][ T318] sock_alloc_send_pskb (net/core/sock.c:2997) [ 238.077520][ T318] packet_sendmsg (net/packet/af_packet.c:2926 net/packet/af_packet.c:3019 net/packet/af_packet.c:3108) [ 238.081469][ T318] [ 238.081870][ T318] Freed by task 299 on cpu 1 at 238.028496s: [ 238.082761][ T318] kasan_save_stack (mm/kasan/common.c:58) [ 238.083481][ T318] kasan_save_track (mm/kasan/common.c:64 (discriminator 5) mm/kasan/common.c:79 (discriminator 5)) [ 238.085348][ T318] kasan_save_free_info (mm/kasan/generic.c:587 (discriminator 1)) [ 238.085900][ T318] __kasan_slab_free (mm/ ---truncated---

CVSS Details

CVSS Score

7.8

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

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

Linux Kernel (Multiple stable branches prior to specific commits)

PoC / Exploit Code

⚠ For Security Research Only

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

python

/*
 * PoC for CVE-2026-23449: Linux Kernel TEQL Double Free
 * This code demonstrates the setup to trigger the race condition.
 * Compile: gcc -o poc_teql poc_teql.c
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <linux/if.h>

int main() {
    printf("[*] CVE-2026-23449 PoC Trigger\n");
    printf("[*] This requires a TEQL device setup and a lockless Qdisc.\n");
    
    // In a real scenario, this would involve:
    // 1. Creating a TEQL device (teql0).
    // 2. Setting a lockless qdisc (e.g., pfifo_fast) as root.
    // 3. Spawning threads to send traffic (teql_master_xmit path).
    // 4. Concurrently resetting the qdisc (teql_destroy/qdisc_reset path).
    
    // Simulated trigger loop
    while(1) {
        // send traffic via socket
        // trigger qdisc reset via netlink
        usleep(100); // attempt to hit race window
    }
    return 0;
}

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-23449
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-23449
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-23449/
[4] VulDB https://vuldb.com/cve/CVE-2026-23449
[5] https://git.kernel.org/stable/c/21c89a0a8de7eadad8d385645a95b3233f23130e
[6] https://git.kernel.org/stable/c/4a233447b941db451ea5f5a0942cffd0f7f7eaae
[7] https://git.kernel.org/stable/c/4e8ebc4c18ea8213d28e6cb867d18fcc67daca21
[8] https://git.kernel.org/stable/c/66360460cab63c248ca5b1070a01c0c29133b960
[9] https://git.kernel.org/stable/c/afbc79a7770b230a9f24bd39271209d6b3682c5f
[10] https://git.kernel.org/stable/c/e9c66d3e7d8557b3308e55c613aa07254fe97611

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-23449", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-03T16:16:31.037", "lastModified": "2026-05-21T00:38:40.837", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: teql: Fix double-free in teql_master_xmit\n\nWhenever a TEQL devices has a lockless Qdisc as root, qdisc_reset should\nbe called using the seq_lock to avoid racing with the datapath. Failure\nto do so may cause crashes like the following:\n\n[ 238.028993][ T318] BUG: KASAN: double-free in skb_release_data (net/core/skbuff.c:1139)\n[ 238.029328][ T318] Free of addr ffff88810c67ec00 by task poc_teql_uaf_ke/318\n[ 238.029749][ T318]\n[ 238.029900][ T318] CPU: 3 UID: 0 PID: 318 Comm: poc_teql_ke Not tainted 7.0.0-rc3-00149-ge5b31d988a41 #704 PREEMPT(full)\n[ 238.029906][ T318] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[ 238.029910][ T318] Call Trace:\n[ 238.029913][ T318] <TASK>\n[ 238.029916][ T318] dump_stack_lvl (lib/dump_stack.c:122)\n[ 238.029928][ T318] print_report (mm/kasan/report.c:379 mm/kasan/report.c:482)\n[ 238.029940][ T318] ? skb_release_data (net/core/skbuff.c:1139)\n[ 238.029944][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)\n...\n[ 238.029957][ T318] ? skb_release_data (net/core/skbuff.c:1139)\n[ 238.029969][ T318] kasan_report_invalid_free (mm/kasan/report.c:221 mm/kasan/report.c:563)\n[ 238.029979][ T318] ? skb_release_data (net/core/skbuff.c:1139)\n[ 238.029989][ T318] check_slab_allocation (mm/kasan/common.c:231)\n[ 238.029995][ T318] kmem_cache_free (mm/slub.c:2637 (discriminator 1) mm/slub.c:6168 (discriminator 1) mm/slub.c:6298 (discriminator 1))\n[ 238.030004][ T318] skb_release_data (net/core/skbuff.c:1139)\n...\n[ 238.030025][ T318] sk_skb_reason_drop (net/core/skbuff.c:1256)\n[ 238.030032][ T318] pfifo_fast_reset (./include/linux/ptr_ring.h:171 ./include/linux/ptr_ring.h:309 ./include/linux/skb_array.h:98 net/sched/sch_generic.c:827)\n[ 238.030039][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)\n...\n[ 238.030054][ T318] qdisc_reset (net/sched/sch_generic.c:1034)\n[ 238.030062][ T318] teql_destroy (./include/linux/spinlock.h:395 net/sched/sch_teql.c:157)\n[ 238.030071][ T318] __qdisc_destroy (./include/net/pkt_sched.h:328 net/sched/sch_generic.c:1077)\n[ 238.030077][ T318] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159)\n[ 238.030089][ T318] ? __pfx_qdisc_graft (net/sched/sch_api.c:1091)\n[ 238.030095][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)\n[ 238.030102][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)\n[ 238.030106][ T318] ? srso_alias_return_thunk (arch/x86/lib/retpoline.S:221)\n[ 238.030114][ T318] tc_get_qdisc (net/sched/sch_api.c:1529 net/sched/sch_api.c:1556)\n...\n[ 238.072958][ T318] Allocated by task 303 on cpu 5 at 238.026275s:\n[ 238.073392][ T318] kasan_save_stack (mm/kasan/common.c:58)\n[ 238.073884][ T318] kasan_save_track (mm/kasan/common.c:64 (discriminator 5) mm/kasan/common.c:79 (discriminator 5))\n[ 238.074230][ T318] __kasan_slab_alloc (mm/kasan/common.c:369)\n[ 238.074578][ T318] kmem_cache_alloc_node_noprof (./include/linux/kasan.h:253 mm/slub.c:4542 mm/slub.c:4869 mm/slub.c:4921)\n[ 238.076091][ T318] kmalloc_reserve (net/core/skbuff.c:616 (discriminator 107))\n[ 238.076450][ T318] __alloc_skb (net/core/skbuff.c:713)\n[ 238.076834][ T318] alloc_skb_with_frags (./include/linux/skbuff.h:1383 net/core/skbuff.c:6763)\n[ 238.077178][ T318] sock_alloc_send_pskb (net/core/sock.c:2997)\n[ 238.077520][ T318] packet_sendmsg (net/packet/af_packet.c:2926 net/packet/af_packet.c:3019 net/packet/af_packet.c:3108)\n[ 238.081469][ T318]\n[ 238.081870][ T318] Freed by task 299 on cpu 1 at 238.028496s:\n[ 238.082761][ T318] kasan_save_stack (mm/kasan/common.c:58)\n[ 238.083481][ T318] kasan_save_track (mm/kasan/common.c:64 (discriminator 5) mm/kasan/common.c:79 (discriminator 5))\n[ 238.085348][ T318] kasan_save_free_info (mm/kasan/generic.c:587 (discriminator 1))\n[ 238.085900][ T318] __kasan_slab_free (mm/\n---truncated---"}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-415"}]}], "configurations": [{"nodes": [{"operator": "OR", "nega ... (truncated)