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Fencer Vulns
critical 9.8

CVE-2024-50154 in the critical feed json

tcp/dccp: Don't use timer_pending() in reqsk_queue_unlink().

published 2024-11-07 2 y ago modified 2026-08-05 3 mo ago also EUVD-2024-45151

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

tcp/dccp: Don't use timer_pending() in reqsk_queue_unlink().

Martin KaFai Lau reported use-after-free [0] in reqsk_timer_handler().

""" We are seeing a use-after-free from a bpf prog attached to trace_tcp_retransmit_synack. The program passes the req->sk to the bpf_sk_storage_get_tracing kernel helper which does check for null before using it. """

The commit 83fccfc3940c ("inet: fix potential deadlock in reqsk_queue_unlink()") added timer_pending() in reqsk_queue_unlink() not to call del_timer_sync() from reqsk_timer_handler(), but it introduced a small race window.

Before the timer is called, expire_timers() calls detach_timer(timer, true) to clear timer->entry.pprev and marks it as not pending.

If reqsk_queue_unlink() checks timer_pending() just after expire_timers() calls detach_timer(), TCP will miss del_timer_sync(); the reqsk timer will continue running and send multiple SYN+ACKs until it expires.

The reported UAF could happen if req->sk is close()d earlier than the timer expiration, which is 63s by default.

The scenario would be

1. inet_csk_complete_hashdance() calls inet_csk_reqsk_queue_drop(), but del_timer_sync() is missed

2. reqsk timer is executed and scheduled again

3. req->sk is accept()ed and reqsk_put() decrements rsk_refcnt, but reqsk timer still has another one, and inet_csk_accept() does not clear req->sk for non-TFO sockets

4. sk is close()d

5. reqsk timer is executed again, and BPF touches req->sk

Let's not use timer_pending() by passing the caller context to __inet_csk_reqsk_queue_drop().

Note that reqsk timer is pinned, so the issue does not happen in most use cases. [1]

[0] BUG: KFENCE: use-after-free read in bpf_sk_storage_get_tracing+0x2e/0x1b0

Use-after-free read at 0x00000000a891fb3a (in kfence-#1): bpf_sk_storage_get_tracing+0x2e/0x1b0 bpf_prog_5ea3e95db6da0438_tcp_retransmit_synack+0x1d20/0x1dda bpf_trace_run2+0x4c/0xc0 tcp_rtx_synack+0xf9/0x100 reqsk_timer_handler+0xda/0x3d0 run_timer_softirq+0x292/0x8a0 irq_exit_rcu+0xf5/0x320 sysvec_apic_timer_interrupt+0x6d/0x80 asm_sysvec_apic_timer_interrupt+0x16/0x20 intel_idle_irq+0x5a/0xa0 cpuidle_enter_state+0x94/0x273 cpu_startup_entry+0x15e/0x260 start_secondary+0x8a/0x90 secondary_startup_64_no_verify+0xfa/0xfb

kfence-#1: 0x00000000a72cc7b6-0x00000000d97616d9, size=2376, cache=TCPv6

allocated by task 0 on cpu 9 at 260507.901592s: sk_prot_alloc+0x35/0x140 sk_clone_lock+0x1f/0x3f0 inet_csk_clone_lock+0x15/0x160 tcp_create_openreq_child+0x1f/0x410 tcp_v6_syn_recv_sock+0x1da/0x700 tcp_check_req+0x1fb/0x510 tcp_v6_rcv+0x98b/0x1420 ipv6_list_rcv+0x2258/0x26e0 napi_complete_done+0x5b1/0x2990 mlx5e_napi_poll+0x2ae/0x8d0 net_rx_action+0x13e/0x590 irq_exit_rcu+0xf5/0x320 common_interrupt+0x80/0x90 asm_common_interrupt+0x22/0x40 cpuidle_enter_state+0xfb/0x273 cpu_startup_entry+0x15e/0x260 start_secondary+0x8a/0x90 secondary_startup_64_no_verify+0xfa/0xfb

freed by task 0 on cpu 9 at 260507.927527s: rcu_core_si+0x4ff/0xf10 irq_exit_rcu+0xf5/0x320 sysvec_apic_timer_interrupt+0x6d/0x80 asm_sysvec_apic_timer_interrupt+0x16/0x20 cpuidle_enter_state+0xfb/0x273 cpu_startup_entry+0x15e/0x260 start_secondary+0x8a/0x90 secondary_startup_64_no_verify+0xfa/0xfb

Patch / fix

  • Linux Linux 4.2, 5.4.293, 5.10.237, 5.15.170, 6.1.115, 6.6.59, 6.11.6, 6.12
  • linux Debian 12 6.1.115-1
  • linux Debian 14, Debian 13 6.11.6-1

debian advisories DEBIAN-CVE-2024-50154

  • linux Ubuntu 22.04 LTS 5.15.0-133.144
  • linux Ubuntu 24.04 LTS 6.8.0-58.60
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1078.85
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1027.29
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1077.86
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1028.30
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1075.81
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1023.27

ubuntu advisories UBUNTU-CVE-2024-50154

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt RHEL 8 4.18.0-553.63.1.rt7.404.el8_10
  • kernel-rt-kvm RHEL 8 4.18.0-553.63.1.rt7.404.el8_10
  • kernel-rt-core RHEL 8 4.18.0-553.63.1.rt7.404.el8_10
  • kernel-rt-modules RHEL 8 4.18.0-553.63.1.rt7.404.el8_10
  • kernel-rt-debug-kvm RHEL 8 4.18.0-553.63.1.rt7.404.el8_10
  • kernel-rt-debug-core RHEL 8 4.18.0-553.63.1.rt7.404.el8_10
  • kernel-rt-debug-modules RHEL 8 4.18.0-553.63.1.rt7.404.el8_10
  • kernel-rt-modules-extra RHEL 8 4.18.0-553.63.1.rt7.404.el8_10

red hat advisories RHSA-2025:11456RHSA-2025:11455RHSA-2025:1658RHSA-2025:0578

  • kernel-livepatch-MICRO-6-0-RT_Update_3 Linux Micro 6.0 13-1.2
  • kernel-livepatch-MICRO-6-0-RT_Update_2 Linux Micro 6.1, Linux Micro 6.0 13-1.1
  • kernel-livepatch-MICRO-6-0_Update_2 Linux Micro 6.1, Linux Micro 6.0 13-1.1
  • kernel-livepatch-MICRO-6-0_Update_3 Linux Micro 6.0 13-1.2
  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-25.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-25.1
  • kernel-livepatch-MICRO-6-0-RT_Update_5 Linux Micro 6.1, Linux Micro 6.0 1-1.1
  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-25.1

suse advisories SUSE-SU-2025:4123-1SUSE-SU-2025:03580-1SUSE-SU-2025:03566-1SUSE-SU-2025:03557-1SUSE-SU-2025:03553-1SUSE-SU-2025:03548-1

  • kernel-source-longterm openSUSE Tumbleweed 6.12.11-1.1
  • kernel-source openSUSE Tumbleweed 6.11.8-1.1

opensuse advisories openSUSE-SU-2025:14705-1openSUSE-SU-2024:14500-1

  • kernel AlmaLinux 8 4.18.0-553.63.1.el8_10
  • perf AlmaLinux 8 4.18.0-553.63.1.el8_10
  • bpftool AlmaLinux 8 4.18.0-553.63.1.el8_10
  • kernel-core AlmaLinux 8 4.18.0-553.63.1.el8_10
  • kernel-tools AlmaLinux 8 4.18.0-553.63.1.el8_10
  • python3-perf AlmaLinux 8 4.18.0-553.63.1.el8_10
  • kernel-modules AlmaLinux 8 4.18.0-553.63.1.el8_10
  • kernel-zfcpdump AlmaLinux 8 4.18.0-553.63.1.el8_10

almalinux advisories ALSA-2025:11455ALSA-2025:11456ALSA-2025:0578

  • kernel-rt Rocky Linux 8 4.18.0-553.63.1.rt7.404.el8_10
  • kernel Rocky Linux 8 4.18.0-553.63.1.el8_10

rocky linux advisories RLSA-2025:11456RLSA-2025:11455

  • kernel CBL-Mariner 2.0 5.15.173.1-1
  • kernel Azure Linux 3.0 6.6.64.2-1

azure linux advisories AZL-52967AZL-52987

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-50154 updated cvss 7.0

kernel: tcp/dccp: Don't use timer_pending() in reqsk_queue_unlink().

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 9) libperf 5.14.0-503.22.1.el9_5, kernel-debuginfo-common-s390x 5.14.0-503.22.1.el9_5, kernel-debuginfo-common-x86_64 5.14.0-503.22.1.el9_5, kernel-debuginfo-common-aarch64 5.14.0-503.22.1.el9_5, kernel-debuginfo-common-ppc64le 5.14.0-503.22.1.el9_5
    fixed: vendor fix RHSA-2025:0578
  • Red Hat CodeReady Linux Builder EUS (v.9.4) libperf 5.14.0-427.55.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.55.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.55.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.55.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.55.1.el9_4
    fixed: vendor fix RHSA-2025:1658
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-503.22.1.el9_5, perf 5.14.0-503.22.1.el9_5, rtla 5.14.0-503.22.1.el9_5, kernel-devel-matched 5.14.0-503.22.1.el9_5, kernel-64k-devel-matched 5.14.0-503.22.1.el9_5, kernel-debug-devel-matched 5.14.0-503.22.1.el9_5, +6 more
    fixed: vendor fix RHSA-2025:0578
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) rv 5.14.0-427.55.1.el9_4, perf 5.14.0-427.55.1.el9_4, rtla 5.14.0-427.55.1.el9_4, kernel-devel-matched 5.14.0-427.55.1.el9_4, kernel-64k-devel-matched 5.14.0-427.55.1.el9_4, kernel-debug-devel-matched 5.14.0-427.55.1.el9_4, +6 more
    fixed: vendor fix RHSA-2025:1658
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.63.1.el8_10, kernel 4.18.0-553.63.1.el8_10, bpftool 4.18.0-553.63.1.el8_10, kernel-core 4.18.0-553.63.1.el8_10, kernel-tools 4.18.0-553.63.1.el8_10, python3-perf 4.18.0-553.63.1.el8_10, +15 more
    fixed: vendor fix RHSA-2025:11455
  • Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.4.0-503.22.1.el9_5, kernel 5.14.0-503.22.1.el9_5, kernel-64k 5.14.0-503.22.1.el9_5, kernel-core 5.14.0-503.22.1.el9_5, kernel-tools 5.14.0-503.22.1.el9_5, python3-perf 5.14.0-503.22.1.el9_5, +29 more
    fixed: vendor fix RHSA-2025:0578
  • Red Hat Enterprise Linux BaseOS EUS (v.9.4) bpftool 7.3.0-427.55.1.el9_4, kernel 5.14.0-427.55.1.el9_4, kernel-64k 5.14.0-427.55.1.el9_4, kernel-core 5.14.0-427.55.1.el9_4, kernel-tools 5.14.0-427.55.1.el9_4, python3-perf 5.14.0-427.55.1.el9_4, +28 more
    fixed: vendor fix RHSA-2025:1658
show 7 more
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.63.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.63.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.63.1.el8_10
    fixed: vendor fix RHSA-2025:11455
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-kvm 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-core 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-modules 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-debug-kvm 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-debug-core 4.18.0-553.63.1.rt7.404.el8_10, +4 more
    fixed: vendor fix RHSA-2025:11456
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-503.22.1.el9_5, kernel-rt-core 5.14.0-503.22.1.el9_5, kernel-rt-modules 5.14.0-503.22.1.el9_5, kernel-rt-debug-core 5.14.0-503.22.1.el9_5, kernel-rt-modules-core 5.14.0-503.22.1.el9_5, kernel-rt-debug-modules 5.14.0-503.22.1.el9_5, +4 more
    fixed: vendor fix RHSA-2025:0578
  • Red Hat Enterprise Linux Real Time EUS (v.9.4) kernel-rt 5.14.0-427.55.1.el9_4, kernel-rt-core 5.14.0-427.55.1.el9_4, kernel-rt-modules 5.14.0-427.55.1.el9_4, kernel-rt-debug-core 5.14.0-427.55.1.el9_4, kernel-rt-modules-core 5.14.0-427.55.1.el9_4, kernel-rt-debug-modules 5.14.0-427.55.1.el9_4, +4 more
    fixed: vendor fix RHSA-2025:1658
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-503.22.1.el9_5, kernel-rt-kvm 5.14.0-503.22.1.el9_5, kernel-rt-core 5.14.0-503.22.1.el9_5, kernel-rt-modules 5.14.0-503.22.1.el9_5, kernel-rt-debug-kvm 5.14.0-503.22.1.el9_5, kernel-rt-debug-core 5.14.0-503.22.1.el9_5, +6 more
    fixed: vendor fix RHSA-2025:0578
  • Red Hat Enterprise Linux Real Time for NFV EUS (v.9.4) kernel-rt 5.14.0-427.55.1.el9_4, kernel-rt-kvm 5.14.0-427.55.1.el9_4, kernel-rt-core 5.14.0-427.55.1.el9_4, kernel-rt-modules 5.14.0-427.55.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.55.1.el9_4, kernel-rt-debug-core 5.14.0-427.55.1.el9_4, +6 more
    fixed: vendor fix RHSA-2025:1658
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-core 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-modules 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-debug-core 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-debug-modules 4.18.0-553.63.1.rt7.404.el8_10, kernel-rt-modules-extra 4.18.0-553.63.1.rt7.404.el8_10, +2 more
    fixed: vendor fix RHSA-2025:11456

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
22 mo ago

Exploit prediction

0.56% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.