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Fencer Vulns
high 7.8

CVE-2024-36904 json

tcp: Use refcount_inc_not_zero() in tcp_twsk_unique().

published 2024-05-30 2 y ago modified 2026-10-15 25 d ago also EUVD-2024-36255

cvss
7.8
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 49%
public exploits
0
none known

Summary

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

tcp: Use refcount_inc_not_zero() in tcp_twsk_unique().

Anderson Nascimento reported a use-after-free splat in tcp_twsk_unique() with nice analysis.

Since commit ec94c2696f0b ("tcp/dccp: avoid one atomic operation for timewait hashdance"), inet_twsk_hashdance() sets TIME-WAIT socket's sk_refcnt after putting it into ehash and releasing the bucket lock.

Thus, there is a small race window where other threads could try to reuse the port during connect() and call sock_hold() in tcp_twsk_unique() for the TIME-WAIT socket with zero refcnt.

If that happens, the refcnt taken by tcp_twsk_unique() is overwritten and sock_put() will cause underflow, triggering a real use-after-free somewhere else.

To avoid the use-after-free, we need to use refcount_inc_not_zero() in tcp_twsk_unique() and give up on reusing the port if it returns false.

[0]: refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 1039313 at lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110 CPU: 0 PID: 1039313 Comm: trigger Not tainted 6.8.6-200.fc39.x86_64 #1 Hardware name: VMware, Inc. VMware20,1/440BX Desktop Reference Platform, BIOS VMW201.00V.21805430.B64.2305221830 05/22/2023 RIP: 0010:refcount_warn_saturate+0xe5/0x110 Code: 42 8e ff 0f 0b c3 cc cc cc cc 80 3d aa 13 ea 01 00 0f 85 5e ff ff ff 48 c7 c7 f8 8e b7 82 c6 05 96 13 ea 01 01 e8 7b 42 8e ff <0f> 0b c3 cc cc cc cc 48 c7 c7 50 8f b7 82 c6 05 7a 13 ea 01 01 e8 RSP: 0018:ffffc90006b43b60 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff888009bb3ef0 RCX: 0000000000000027 RDX: ffff88807be218c8 RSI: 0000000000000001 RDI: ffff88807be218c0 RBP: 0000000000069d70 R08: 0000000000000000 R09: ffffc90006b439f0 R10: ffffc90006b439e8 R11: 0000000000000003 R12: ffff8880029ede84 R13: 0000000000004e20 R14: ffffffff84356dc0 R15: ffff888009bb3ef0 FS: 00007f62c10926c0(0000) GS:ffff88807be00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020ccb000 CR3: 000000004628c005 CR4: 0000000000f70ef0 PKRU: 55555554 Call Trace: <TASK> ? refcount_warn_saturate+0xe5/0x110 ? __warn+0x81/0x130 ? refcount_warn_saturate+0xe5/0x110 ? report_bug+0x171/0x1a0 ? refcount_warn_saturate+0xe5/0x110 ? handle_bug+0x3c/0x80 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? refcount_warn_saturate+0xe5/0x110 tcp_twsk_unique+0x186/0x190 __inet_check_established+0x176/0x2d0 __inet_hash_connect+0x74/0x7d0 ? __pfx___inet_check_established+0x10/0x10 tcp_v4_connect+0x278/0x530 __inet_stream_connect+0x10f/0x3d0 inet_stream_connect+0x3a/0x60 __sys_connect+0xa8/0xd0 __x64_sys_connect+0x18/0x20 do_syscall_64+0x83/0x170 entry_SYSCALL_64_after_hwframe+0x78/0x80 RIP: 0033:0x7f62c11a885d Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a3 45 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007f62c1091e58 EFLAGS: 00000296 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 0000000020ccb004 RCX: 00007f62c11a885d RDX: 0000000000000010 RSI: 0000000020ccb000 RDI: 0000000000000003 RBP: 00007f62c1091e90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000296 R12: 00007f62c10926c0 R13: ffffffffffffff88 R14: 0000000000000000 R15: 00007ffe237885b0 </TASK>

Patch / fix

  • Linux Linux 4.19.314, 5.4.276, 5.10.217, 5.15.159, 6.1.91, 6.6.31, 6.8.10, 6.9
  • Siemens RUGGEDCOM RST2428P V3.1
  • Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family V3.1
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem V1.1.1
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • linux Debian 12 6.1.94-1
  • linux Debian 14, Debian 13 6.8.11-1

debian advisories DEBIAN-CVE-2024-36904

  • linux Ubuntu 20.04 LTS 5.4.0-192.212
  • linux Ubuntu 22.04 LTS 5.15.0-118.128
  • linux Ubuntu 24.04 LTS 6.8.0-40.40
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1130.140
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1067.73
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1013.14
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1134.143
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1066.74

ubuntu advisories UBUNTU-CVE-2024-36904

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 4.18.0-553.16.1.rt7.357.el8_10
  • kernel-rt-kvm RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
  • kernel-rt-core RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
  • kernel-rt-modules RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
  • kernel-rt-debug-kvm RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
  • kernel-rt-debug-core RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
  • kernel-rt-debug-modules RHEL 8 4.18.0-553.16.1.rt7.357.el8_10
  • kernel-rt-modules-extra RHEL 8 4.18.0-553.16.1.rt7.357.el8_10

red hat advisories RHSA-2024:5102RHSA-2024:5101RHSA-2024:6206RHSA-2024:4823RHSA-2024:4831RHSA-2024:4583

  • kernel-rt Linux Micro 6.0 6.4.0-9.1
  • kernel-source-rt Linux Micro 6.0 6.4.0-9.1
  • kernel-source Linux Micro 6.0 6.4.0-18.1
  • kernel-default Linux Micro 6.0 6.4.0-18.1
  • kernel-kvmsmall Linux Micro 6.0 6.4.0-18.1
  • kernel-default-base Linux Micro 6.0 6.4.0-17.1.1.51
  • kernel-livepatch-SLE15-SP5_Update_10 SLE Live Patching 15 SP5 13-150500.11.8.1
  • kernel-livepatch-SLE15-SP4_Update_26 SLE Live Patching 15 SP4 10-150400.9.6.1

suse advisories SUSE-SU-2025:20028-1SUSE-SU-2025:20008-1SUSE-SU-2025:0266-1SUSE-SU-2025:0264-1SUSE-SU-2025:0261-1SUSE-SU-2025:0260-1

  • kernel AlmaLinux 8 4.18.0-553.16.1.el8_10
  • perf AlmaLinux 8 4.18.0-553.16.1.el8_10
  • bpftool AlmaLinux 8 4.18.0-553.16.1.el8_10
  • kernel-core AlmaLinux 8 4.18.0-553.16.1.el8_10
  • kernel-tools AlmaLinux 8 4.18.0-553.16.1.el8_10
  • python3-perf AlmaLinux 8 4.18.0-553.16.1.el8_10
  • kernel-modules AlmaLinux 8 4.18.0-553.16.1.el8_10
  • kernel-zfcpdump AlmaLinux 8 4.18.0-553.16.1.el8_10

almalinux advisories ALSA-2024:5101ALSA-2024:5102ALSA-2024:4583

  • kernel Rocky Linux 8 4.18.0-553.16.1.el8_10.cloud.0.1
  • kernel-rt Rocky Linux 8 4.18.0-553.16.1.rt7.357.el8_10
  • kernel Rocky Linux 8 4.18.0-553.16.1.el8_10
  • kernel Rocky Linux 9 5.14.0-427.26.1.el9_4

rocky linux advisories RXSA-2024:5101RLSA-2024:5102RLSA-2024:5101RLSA-2024:4583

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-2024-36904 updated cvss 7.0

kernel: tcp: Use refcount_inc_not_zero() in tcp_twsk_unique().

  • 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 Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available
  • Red Hat CodeReady Linux Builder EUS (v.8.8) kernel-debuginfo-common-x86_64 4.18.0-477.70.1.el8_8, kernel-debuginfo-common-aarch64 4.18.0-477.70.1.el8_8, kernel-debuginfo-common-ppc64le 4.18.0-477.70.1.el8_8
    fixed: vendor fix RHSA-2024:6206
  • Red Hat CodeReady Linux Builder EUS (v.9.2) kernel-debuginfo-common-s390x 5.14.0-284.75.1.el9_2, kernel-debuginfo-common-x86_64 5.14.0-284.75.1.el9_2, kernel-debuginfo-common-aarch64 5.14.0-284.75.1.el9_2, kernel-debuginfo-common-ppc64le 5.14.0-284.75.1.el9_2
    fixed: vendor fix RHSA-2024:4823
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-427.26.1.el9_4, perf 5.14.0-427.26.1.el9_4, rtla 5.14.0-427.26.1.el9_4, kernel-devel-matched 5.14.0-427.26.1.el9_4, kernel-64k-devel-matched 5.14.0-427.26.1.el9_4, kernel-debug-devel-matched 5.14.0-427.26.1.el9_4, +6 more
    fixed: vendor fix RHSA-2024:4583
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) perf 5.14.0-284.75.1.el9_2, rtla 5.14.0-284.75.1.el9_2, kernel-devel-matched 5.14.0-284.75.1.el9_2, kernel-64k-devel-matched 5.14.0-284.75.1.el9_2, kernel-debug-devel-matched 5.14.0-284.75.1.el9_2, kernel-debuginfo-common-s390x 5.14.0-284.75.1.el9_2, +5 more
    fixed: vendor fix RHSA-2024:4823
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.16.1.el8_10, kernel 4.18.0-553.16.1.el8_10, bpftool 4.18.0-553.16.1.el8_10, kernel-core 4.18.0-553.16.1.el8_10, kernel-tools 4.18.0-553.16.1.el8_10, python3-perf 4.18.0-553.16.1.el8_10, +15 more
    fixed: vendor fix RHSA-2024:5101
  • Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.3.0-427.26.1.el9_4, kernel 5.14.0-427.26.1.el9_4, kernel-64k 5.14.0-427.26.1.el9_4, kernel-core 5.14.0-427.26.1.el9_4, kernel-tools 5.14.0-427.26.1.el9_4, python3-perf 5.14.0-427.26.1.el9_4, +28 more
    fixed: vendor fix RHSA-2024:4583
show 12 more
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) perf 4.18.0-372.119.1.el8_6, kernel 4.18.0-372.119.1.el8_6, bpftool 4.18.0-372.119.1.el8_6, kernel-core 4.18.0-372.119.1.el8_6, kernel-tools 4.18.0-372.119.1.el8_6, python3-perf 4.18.0-372.119.1.el8_6, +8 more Red Hat Enterprise Linux BaseOS E4S (v.8.6) perf 4.18.0-372.119.1.el8_6, kernel 4.18.0-372.119.1.el8_6, bpftool 4.18.0-372.119.1.el8_6, kernel-core 4.18.0-372.119.1.el8_6, kernel-tools 4.18.0-372.119.1.el8_6, python3-perf 4.18.0-372.119.1.el8_6, +15 more
    fixed: vendor fix RHSA-2024:5692
  • Red Hat Enterprise Linux BaseOS EUS (v.8.8) perf 4.18.0-477.70.1.el8_8, kernel 4.18.0-477.70.1.el8_8, bpftool 4.18.0-477.70.1.el8_8, kernel-core 4.18.0-477.70.1.el8_8, kernel-tools 4.18.0-477.70.1.el8_8, python3-perf 4.18.0-477.70.1.el8_8, +15 more
    fixed: vendor fix RHSA-2024:6206
  • Red Hat Enterprise Linux BaseOS EUS (v.9.2) bpftool 7.0.0-284.75.1.el9_2, kernel 5.14.0-284.75.1.el9_2, kernel-64k 5.14.0-284.75.1.el9_2, kernel-core 5.14.0-284.75.1.el9_2, kernel-tools 5.14.0-284.75.1.el9_2, python3-perf 5.14.0-284.75.1.el9_2, +28 more
    fixed: vendor fix RHSA-2024:4823
  • Red Hat Enterprise Linux BaseOS TUS (v.8.6) perf 4.18.0-372.119.1.el8_6, kernel 4.18.0-372.119.1.el8_6, bpftool 4.18.0-372.119.1.el8_6, kernel-core 4.18.0-372.119.1.el8_6, kernel-tools 4.18.0-372.119.1.el8_6, python3-perf 4.18.0-372.119.1.el8_6, +8 more
    fixed: vendor fix RHSA-2024:5692
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.16.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.16.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.16.1.el8_10
    fixed: vendor fix RHSA-2024:5101
  • Red Hat Enterprise Linux CRB (v. 9) libperf 5.14.0-427.26.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.26.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.26.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.26.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.26.1.el9_4
    fixed: vendor fix RHSA-2024:4583
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-kvm 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-core 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-modules 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-kvm 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-core 4.18.0-553.16.1.rt7.357.el8_10, +4 more
    fixed: vendor fix RHSA-2024:5102
  • Red Hat Enterprise Linux NFV (v. 9) kernel-rt 5.14.0-427.26.1.el9_4, kernel-rt-kvm 5.14.0-427.26.1.el9_4, kernel-rt-core 5.14.0-427.26.1.el9_4, kernel-rt-modules 5.14.0-427.26.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.26.1.el9_4, kernel-rt-debug-core 5.14.0-427.26.1.el9_4, +6 more
    fixed: vendor fix RHSA-2024:4583
  • Red Hat Enterprise Linux Real Time EUS (v.9.2) kernel-rt 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-core 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-modules 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-debug-core 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-modules-core 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-debug-modules 5.14.0-284.75.1.rt14.360.el9_2, +4 more Red Hat Enterprise Linux Real Time for NFV EUS (v.9.2) kernel-rt 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-kvm 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-core 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-modules 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-debug-kvm 5.14.0-284.75.1.rt14.360.el9_2, kernel-rt-debug-core 5.14.0-284.75.1.rt14.360.el9_2, +6 more
    fixed: vendor fix RHSA-2024:4831
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-core 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-modules 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-core 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-debug-modules 4.18.0-553.16.1.rt7.357.el8_10, kernel-rt-modules-extra 4.18.0-553.16.1.rt7.357.el8_10, +2 more
    fixed: vendor fix RHSA-2024:5102
  • Red Hat Enterprise Linux RT (v. 9) kernel-rt 5.14.0-427.26.1.el9_4, kernel-rt-core 5.14.0-427.26.1.el9_4, kernel-rt-modules 5.14.0-427.26.1.el9_4, kernel-rt-debug-core 5.14.0-427.26.1.el9_4, kernel-rt-modules-core 5.14.0-427.26.1.el9_4, kernel-rt-debug-modules 5.14.0-427.26.1.el9_4, +4 more
    fixed: vendor fix RHSA-2024:4583
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) kernel-doc 5.14.0-284.75.1.el9_2 Red Hat Enterprise Linux BaseOS AUS (v.8.6) kernel-doc 4.18.0-372.119.1.el8_6 Red Hat Enterprise Linux BaseOS E4S (v.8.6) kernel-doc 4.18.0-372.119.1.el8_6 Red Hat Enterprise Linux BaseOS TUS (v.8.6) kernel-doc 4.18.0-372.119.1.el8_6
    not affected: vulnerable code not present

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 ICSA-24-102-01 updated cvss 5.5

Siemens SIMATIC S7-1500 TM MFP

  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-25-226-15 updated cvss 5.5

Siemens SINEC OS

  • Siemens RUGGEDCOM RST2428P (6GK6242-6PA00) < 3.1 Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family < 3.1
    affected: fixed in V3.1 support.industry.siemens.com
  • Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family
    not affected

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-23-348-10 updated cvss 5.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

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

Affected products

  • Linux Linux
  • Siemens RUGGEDCOM RST2428P
  • Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family
  • Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

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.