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VulnerabilityPublished Updated

CVE-2025-39993: Linux kernel · media: rc: fix races with imon_disconnect()

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 7.8 High · fixed in 4.4.0-1151.157 : patch Linux kernel soon.

Data as of 28 Oct 2026, 11:20 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 4.4.0-1151.157, 4.15.0-1196.211~14.04.1, 4.4.0-277.311~14.04.1 +115
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Oct 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threatsAffected
  • <6.17.0-6.6
Fixed in
  • 6.17.0-6.6
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1006.6
Fixed in
  • 6.17.0-1006.6
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threatsAffected
  • 6.17.0-1003.3 – 6.17.0-1017.17
10 affected builds
Fixed in–
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1003.3
Fixed in
  • 6.17.0-1003.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and has been incorporated into multiple Linux kernel versions. Users should update their Linux kernel to one of the fixed versions listed (e.g., 4.4.0-1151.157, 4.15.0-1196.211~14.04.1, and others) to remediate this issue. After updating, a system reboot is required to apply the fix. No additional mitigation steps are necessary beyond applying the official kernel updates.

Description

CVE-2025-39993 is a use-after-free vulnerability in the Linux kernel's media remote control (rc) subsystem, specifically in the iMON driver. The flaw arises because the driver improperly releases USB device references during disconnect without coordinating with ongoing operations, leading to potential use-after-free conditions. This can cause system crashes or allow an attacker with local privileges to compromise system integrity. The issue has been fixed by adding proper synchronization and early exit checks in affected functions. Multiple Linux kernel versions are affected, and patches are available.

References

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