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VulnerabilityPublished Updated

CVE-2026-23428: Linux kernel · ksmbd: fix use-after-free of share_conf in compound request

Affects Linux kernelSource GCVE Database

0
Authoritative record:CVE-2026-23428· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · fixed in 5.15.0-1111.118~20.04.1 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 26% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.15.0-1111.118~20.04.1, 5.15.0-1116.125~20.04.1, 5.15.0-1111.121~20.04.1 +69
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Apr 2026

  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@6.17.0-40.40?arch=source&distro=questingOther threatsAffected
  • <6.17.0-40.40
Fixed in
  • 6.17.0-40.40
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1019.19
Fixed in
  • 6.17.0-1019.19
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1020.20?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1004.4 – 6.17.0-1020.20
16 affected builds
Fixed in–
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?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@6.17.0-1020.22?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1020.22
Fixed in
  • 6.17.0-1020.22
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1018.18?arch=source&distro=questingOther threatsAffected
  • <6.17.0-1018.18
Fixed in
  • 6.17.0-1018.18

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 released by Ubuntu as part of their Linux kernel updates. Users should update their Linux kernel packages to the fixed versions listed in the Ubuntu security advisories USN-8490-1 and USN-8491-1 and reboot their systems to apply the fixes. Due to an ABI change, recompilation and reinstallation of third-party kernel modules may be necessary. Follow the vendor's update instructions carefully to fully remediate the vulnerability.

Description

A use-after-free vulnerability in the Linux kernel's ksmbd SMB network file system component was resolved. The vulnerability occurs when compound SMB2 requests reuse a tree connection object without validating its state, potentially leading to dereferencing freed memory. This flaw could allow an attacker to cause system crashes or execute arbitrary code. The issue has been fixed in updated Linux kernel versions. Users should apply the official kernel updates and reboot to mitigate the vulnerability.

References

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