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Fencer Intel
high 7.8

CVE-2025-39993 json

media: rc: fix races with imon_disconnect()

published last yr. modified 21d ago also EUVD-2025-34580

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits
0
none known

Summary

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

media: rc: fix races with imon_disconnect()

Syzbot reports a KASAN issue as below: BUG: KASAN: use-after-free in __create_pipe include/linux/usb.h:1945 [inline] BUG: KASAN: use-after-free in send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627 Read of size 4 at addr ffff8880256fb000 by task syz-executor314/4465

CPU: 2 PID: 4465 Comm: syz-executor314 Not tainted 6.0.0-rc1-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:317 [inline] print_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433 kasan_report+0xb1/0x1e0 mm/kasan/report.c:495 __create_pipe include/linux/usb.h:1945 [inline] send_packet+0xa2d/0xbc0 drivers/media/rc/imon.c:627 vfd_write+0x2d9/0x550 drivers/media/rc/imon.c:991 vfs_write+0x2d7/0xdd0 fs/read_write.c:576 ksys_write+0x127/0x250 fs/read_write.c:631 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The iMON driver improperly releases the usb_device reference in imon_disconnect without coordinating with active users of the device.

Specifically, the fields usbdev_intf0 and usbdev_intf1 are not protected by the users counter (ictx->users). During probe, imon_init_intf0 or imon_init_intf1 increments the usb_device reference count depending on the interface. However, during disconnect, usb_put_dev is called unconditionally, regardless of actual usage.

As a result, if vfd_write or other operations are still in progress after disconnect, this can lead to a use-after-free of the usb_device pointer.

Thread 1 vfd_write Thread 2 imon_disconnect ... if usb_put_dev(ictx->usbdev_intf0) else usb_put_dev(ictx->usbdev_intf1) ... while send_packet if pipe = usb_sndintpipe( ictx->usbdev_intf0) UAF else pipe = usb_sndctrlpipe( ictx->usbdev_intf0, 0) UAF

Guard access to usbdev_intf0 and usbdev_intf1 after disconnect by checking ictx->disconnected in all writer paths. Add early return with -ENODEV in send_packet(), vfd_write(), lcd_write() and display_open() if the device is no longer present.

Set and read ictx->disconnected under ictx->lock to ensure memory synchronization. Acquire the lock in imon_disconnect() before setting the flag to synchronize with any ongoing operations.

Ensure writers exit early and safely after disconnect before the USB core proceeds with cleanup.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Patch / fix

  • Linux Linux 5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.110, 6.12.51, 6.16.11, 6.17.1, 6.18
  • linux Debian 12 6.1.158-1
  • linux Debian 13 6.12.57-1
  • linux Debian 14 6.16.11-1

debian advisories DEBIAN-CVE-2025-39993

  • linux Ubuntu 22.04 LTS 5.15.0-164.174
  • linux Ubuntu 24.04 LTS 6.8.0-90.91
  • linux Ubuntu 25.10 6.17.0-6.6
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1098.105
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1044.46
  • linux-aws Ubuntu 25.10 6.17.0-1003.3
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1098.107
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1045.48

ubuntu advisories UBUNTU-CVE-2025-39993

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 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-kvm RHEL 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-core RHEL 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-modules RHEL 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-debug-kvm RHEL 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-debug-core RHEL 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-debug-modules RHEL 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-modules-extra RHEL 8 4.18.0-553.92.1.rt7.433.el8_10

red hat advisories RHSA-2026:3685RHSA-2026:3634RHSA-2026:1512RHSA-2026:1445RHSA-2026:1442RHSA-2026:0533

  • kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
  • kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
  • kernel-rt_debug Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
  • kernel-source-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
  • kernel-rt Linux Micro 6.2 6.12.0-160000.7.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.7.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.7.1
  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.7.1

suse advisories SUSE-SU-2025:4301-1SUSE-SU-2025:21080-1SUSE-SU-2025:21147-1SUSE-SU-2025:21180-1SUSE-SU-2026:20561-1SUSE-SU-2025:21052-1

  • kernel-source-longterm openSUSE Tumbleweed 6.18.16-1.1
  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.7.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.7.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.7.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.7.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.7.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.7.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.7.1

opensuse advisories openSUSE-SU-2026:10301-1openSUSE-SU-2025:20091-1openSUSE-SU-2025:15671-1

  • kernel-rt AlmaLinux 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-core AlmaLinux 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-modules AlmaLinux 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-debug-core AlmaLinux 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-debug-modules AlmaLinux 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-modules-extra AlmaLinux 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel-rt-debug-modules-extra AlmaLinux 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel AlmaLinux 8 4.18.0-553.92.1.el8_10

almalinux advisories ALSA-2026:0443ALSA-2026:0444

  • kernel-rt Rocky Linux 8 4.18.0-553.92.1.rt7.433.el8_10
  • kernel Rocky Linux 8 4.18.0-553.92.1.el8_10

rocky linux advisories RLSA-2026:0443RLSA-2026:0444

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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-2025-39993 updated cvss 7.0

kernel: media: rc: fix races with imon_disconnect()

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux BaseOS (v. 8) kernel 4.18.0-553.92.1.el8_10, bpftool 4.18.0-553.92.1.el8_10, kernel-core 4.18.0-553.92.1.el8_10, kernel-tools 4.18.0-553.92.1.el8_10, python3-perf 4.18.0-553.92.1.el8_10, kernel-modules 4.18.0-553.92.1.el8_10, +10 more
    fixed: vendor fix RHSA-2026:0444
  • Red Hat Enterprise Linux BaseOS AUS (v. 8.2) perf 4.18.0-193.183.1.el8_2, kernel 4.18.0-193.183.1.el8_2, bpftool 4.18.0-193.183.1.el8_2, kernel-core 4.18.0-193.183.1.el8_2, kernel-tools 4.18.0-193.183.1.el8_2, python3-perf 4.18.0-193.183.1.el8_2, +8 more
    fixed: vendor fix RHSA-2026:1512
  • Red Hat Enterprise Linux BaseOS AUS (v.8.4) perf 4.18.0-305.183.1.el8_4, kernel 4.18.0-305.183.1.el8_4, bpftool 4.18.0-305.183.1.el8_4, kernel-core 4.18.0-305.183.1.el8_4, kernel-tools 4.18.0-305.183.1.el8_4, python3-perf 4.18.0-305.183.1.el8_4, +8 more
    fixed: vendor fix RHSA-2026:0533
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) perf 4.18.0-372.177.1.el8_6, kernel 4.18.0-372.177.1.el8_6, bpftool 4.18.0-372.177.1.el8_6, kernel-core 4.18.0-372.177.1.el8_6, kernel-tools 4.18.0-372.177.1.el8_6, python3-perf 4.18.0-372.177.1.el8_6, +8 more Red Hat Enterprise Linux BaseOS E4S (v.8.6) perf 4.18.0-372.177.1.el8_6, kernel 4.18.0-372.177.1.el8_6, bpftool 4.18.0-372.177.1.el8_6, kernel-core 4.18.0-372.177.1.el8_6, kernel-tools 4.18.0-372.177.1.el8_6, python3-perf 4.18.0-372.177.1.el8_6, +15 more
    fixed: vendor fix RHSA-2026:1442
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) perf 4.18.0-477.126.1.el8_8, kernel 4.18.0-477.126.1.el8_8, bpftool 4.18.0-477.126.1.el8_8, kernel-core 4.18.0-477.126.1.el8_8, kernel-tools 4.18.0-477.126.1.el8_8, python3-perf 4.18.0-477.126.1.el8_8, +9 more
    fixed: vendor fix RHSA-2026:1445
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) perf 4.18.0-305.183.1.el8_4, kernel 4.18.0-305.183.1.el8_4, bpftool 4.18.0-305.183.1.el8_4, kernel-core 4.18.0-305.183.1.el8_4, kernel-tools 4.18.0-305.183.1.el8_4, python3-perf 4.18.0-305.183.1.el8_4, +8 more
    fixed: vendor fix RHSA-2026:0533
  • Red Hat Enterprise Linux BaseOS TUS (v.8.6) perf 4.18.0-372.177.1.el8_6, kernel 4.18.0-372.177.1.el8_6, bpftool 4.18.0-372.177.1.el8_6, kernel-core 4.18.0-372.177.1.el8_6, kernel-tools 4.18.0-372.177.1.el8_6, python3-perf 4.18.0-372.177.1.el8_6, +8 more
    fixed: vendor fix RHSA-2026:1442
show 6 more
  • Red Hat Enterprise Linux BaseOS TUS (v.8.8) perf 4.18.0-477.126.1.el8_8, kernel 4.18.0-477.126.1.el8_8, bpftool 4.18.0-477.126.1.el8_8, kernel-core 4.18.0-477.126.1.el8_8, kernel-tools 4.18.0-477.126.1.el8_8, python3-perf 4.18.0-477.126.1.el8_8, +8 more
    fixed: vendor fix RHSA-2026:1445
  • Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel 4.18.0-553.92.1.el8_10
    fixed: vendor fix RHSA-2026:0444
  • Red Hat Enterprise Linux for Real Time (v. 7 ELS) kernel-rt 3.10.0-1160.147.1.rt56.1299.el7, kernel-rt-trace 3.10.0-1160.147.1.rt56.1299.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.147.1.rt56.1299.el7
    fixed: vendor fix RHSA-2026:3634
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-kvm 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-core 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-modules 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-debug-kvm 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-debug-core 4.18.0-553.92.1.rt7.433.el8_10, +3 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-core 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-modules 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-debug-core 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-debug-modules 4.18.0-553.92.1.rt7.433.el8_10, kernel-rt-modules-extra 4.18.0-553.92.1.rt7.433.el8_10, +1 more
    fixed: vendor fix RHSA-2026:0443
  • Red Hat Enterprise Linux Server (v. 7 ELS) perf 3.10.0-1160.147.1.el7, kernel 3.10.0-1160.147.1.el7, bpftool 3.10.0-1160.147.1.el7, python-perf 3.10.0-1160.147.1.el7, kernel-kdump 3.10.0-1160.147.1.el7, kernel-tools 3.10.0-1160.147.1.el7, +7 more Red Hat Enterprise Linux Server Optional (v. 7 ELS) kernel-debuginfo-common-ppc64 3.10.0-1160.147.1.el7, kernel-debuginfo-common-x86_64 3.10.0-1160.147.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-1160.147.1.el7
    fixed: vendor fix RHSA-2026:3685
  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.92.1.el8_10, kernel-debuginfo-common-s390x 4.18.0-553.92.1.el8_10, kernel-debuginfo-common-x86_64 4.18.0-553.92.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.92.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.92.1.el8_10 Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.92.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.92.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.92.1.el8_10 Red Hat Enterprise Linux NFV (v. 8) kernel-rt-debuginfo-common-x86_64 4.18.0-553.92.1.rt7.433.el8_10 Red Hat Enterprise Linux RT (v. 8) kernel-rt-debuginfo-common-x86_64 4.18.0-553.92.1.rt7.433.el8_10
    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 SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-09).

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

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Intel 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.