Intel

CVE-2026-53260

Security update for the Linux Kernel

criticalEPSS 0.4%

Description

In the Linux kernel, the following vulnerability has been resolved: tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). syzbot reported a weird reqsk->rsk_refcnt underflow in __inet_csk_reqsk_queue_drop(). The captured reqsk_put() in __inet_csk_reqsk_queue_drop() is called only when it successfully removes reqsk from ehash. Moreover, reqsk_timer_handler() calls another reqsk_put() after that. This indicates that the reqsk was missing both refcnts for ehash and the timer itself. Since all the syzbot reports had PREEMPT_RT enabled, the only possible scenario is that reqsk_queue_hash_req() is preempted after mod_timer() and before refcount_set(), and then the timer triggered after 1s aborts the reqsk due to its listener's close(). Let's wrap mod_timer() and refcount_set() with preempt_disable_nested() and preempt_enable_nested(). Note that inet_ehash_insert() holds the normal spin_lock() (mutex in PREEMPT_RT), so it must be called outside of preempt_disable_nested(), but this is fine. The lookup path just ignores 0 sk_refcnt entries in ehash and tries to create another reqsk, but this will fail at inet_ehash_insert(). [0]: refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16 Modules linked in: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28 Code: e4 7d d1 0a 67 48 0f b9 3a eb 4a e8 38 3d 23 fd 48 8d 3d e1 7d d1 0a 67 48 0f b9 3a eb 37 e8 25 3d 23 fd 48 8d 3d de 7d d1 0a <67> 48 0f b9 3a eb 24 e8 12 3d 23 fd 48 8d 3d db 7d d1 0a 67 48 0f RSP: 0000:ffffc90000157948 EFLAGS: 00010246 RAX: ffffffff84a1301b RBX: 0000000000000003 RCX: ffff88801ca98000 RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8f72ae00 RBP: ffffffff99ae3b01 R08: ffff88801ca98000 R09: 0000000000000005 R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880425ef568 R13: ffff8880425ef4f8 R14: ffff8880425ef578 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888126386000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7b46710e9c CR3: 000000000dbb6000 CR4: 00000000003526f0 Call Trace: <TASK> __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] reqsk_put include/net/request_sock.h:136 [inline] __inet_csk_reqsk_queue_drop+0x3ce/0x440 net/ipv4/inet_connection_sock.c:1007 reqsk_timer_handler+0x651/0xdf0 net/ipv4/inet_connection_sock.c:1137 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>

Source: SUSE_CSAFSUSE_CSAFSUSE_CSAFSUSE_CSAFUBUNTU_USNUBUNTU_USNUBUNTU_USNUBUNTU_USNUBUNTU_USNUBUNTU_USNUBUNTU_USNUBUNTU_USNBSIBSI_CSAFUBUNTU_USNDEBIAN_DSACVELISTV5NVDCVEORG

Metrics

Severity
critical
Priority score
238.98
KEV status
—
Exploit maturity
no public PoC known
XIEM Effective CVSS
9.8
Source: nvd-v3
CVSS v3
9.8
CVSS v4
—
EPSS percentile
30.1 %
Elevated — this CVE ranks above at least 10% of all CVEs scored today.
EPSS score
0.4 %
Low — model estimates < 1% exploitation likelihood.
Published
2026-09-09 12:14 UTC
CWE
—

Reanalysis & status changes

Chronological NVD audit events for this CVE — reanalyses, CVSS updates, CPE diffs.

  1. CVE Modified2026-07-24 15:18 UTC· 416baaa9-dc9f-4396-8d5f-8c081fb06d67
    • Reference: https://git.kernel.org/stable/c/889fc99967007e2493833515a645cb2d800f6742
    • Reference: https://git.kernel.org/stable/c/de5a46f3b2c8d3cd20afa158bd3a725e3e3d6fd3
    • Affected: Linux, Linux → Linux, Linux

Affected operating systems

  • linux

    amazon / amazon_linux

  • linux

    suse / basesystem_module15

  • linux

    debian / debian_linux11.0

  • linux

    debian / debian_linux12.0

  • linux

    debian / debian_linux13.0

  • linux

    suse / development_tools_module15

  • linux

    redhat / enterprise_linux10.0

  • linux

    redhat / enterprise_linux8.0

  • linux

    redhat / enterprise_linux9.0

  • linux

    redhat / enterprise_linux_aus8.4

  • linux

    redhat / enterprise_linux_aus8.6

  • linux

    redhat / enterprise_linux_eus10.0

  • linux

    redhat / enterprise_linux_eus8.4

  • linux

    redhat / enterprise_linux_eus9.4

  • linux

    redhat / enterprise_linux_eus9.6

  • linux

    redhat / enterprise_linux_tus8.6

  • linux

    redhat / enterprise_linux_tus8.8

  • linux

    redhat / enterprise_linux_update_services_for_sap_solutions8.6

  • linux

    redhat / enterprise_linux_update_services_for_sap_solutions8.8

  • linux

    redhat / enterprise_linux_update_services_for_sap_solutions9.0

  • linux

    redhat / enterprise_linux_update_services_for_sap_solutions9.2

  • linux

    opensuse / leap15.3

  • linux

    opensuse / leap15.4

  • linux

    opensuse / leap15.5

Affected products

Products and version ranges extracted from the vendor/CERT advisory. A range like „<4.14.6“ implies the update recommendation „upgrade to 4.14.6 or later“.

  • AMD

    ProzessorEPYC Series

  • AMD

    ProzessorRyzen

  • arista

    cloudvision_agni2024.4.0 – 2025.2.2

  • arista

    cloudvision_portal2024.2.0 – 2026.1.0

  • arista

    velocloud_edge4.5.0 – 6.4.1

  • arista

    velocloud_gateway

  • arista

    velocloud_orchestrator

  • Dell

    NetWorkerVirtual Edition

  • Dell

    PowerProtect Data Domain7.10.1.70

  • Dell

    PowerProtect Data Domain7.13.1.40

  • Dell

    PowerProtect Data Domain8.3.1.10

  • Dell

    PowerProtect Data Domain8.4.0.0

  • IBM

    QRadar SIEM7.5.0 UP10 IF01

  • IBM

    QRadar SIEM7.5.0 UP11

  • IBM

    QRadar SIEM<7.5.0 UP15 IF06

  • IBM

    Security Guardium12

  • IBM

    Storage Scale6.1.9.5

  • IBM

    Storage Scale6.2.2.0

  • Juniper

    Junos Space24.1R2

  • Oracle

    VM3

  • redhat

    openshift_container_platform4.12 – 4.12.89

  • redhat

    openshift_container_platform4.13 – 4.13.66

  • redhat

    openshift_container_platform4.14 – 4.14.65

  • redhat

    openshift_container_platform4.15 – 4.15.64

References & sources

Linked CVEs

Show 51 more CVEs
IDCVE-2026-53260