CVE-2026-64137: Linux kernel · smb: client: require net admin for CIFS SWN netlink
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +67
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 20 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
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 should be applied promptly to affected Linux kernel versions. The fix enforces the requirement of CAP_NET_ADMIN capability for sending witness-notify commands and joining multicast groups via the CIFS SWN netlink interface. Users should follow vendor advisories such as the Ubuntu Security Notice USN-8593-1 to update their systems. No additional mitigation steps are indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel SMB client allowed unprivileged local processes to send witness-notify commands and join multicast groups without requiring CAP_NET_ADMIN permissions. This could expose sensitive session information such as usernames, domains, and passwords. The issue was fixed by enforcing CAP_NET_ADMIN capability checks for these operations. Multiple Linux kernel versions prior to the fixed releases are affected. A patch is available and should be applied to mitigate the risk.
References
- ubuntu.com/security/CVE-2026-64137 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-64137 (opens in a new tab)
- git.kernel.org/linus/d1ebfce2c1d161186a82e77590bf7da2ea1bce91 (opens in a new tab)
- ubuntu.com/security/notices/USN-8593-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8603-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8618-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8663-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8664-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8729-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8761-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8729-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8761-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8781-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8729-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8761-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8802-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8729-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8729-5 (opens in a new tab)