CVE-2026-72422: Linux kernel · ksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 5.15.0-1117.124~20.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 53% 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 +43
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Aug 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 to affected Linux kernel versions. The fix serializes access to the vulnerable shared pointer using the connection lock to prevent use-after-free. No additional mitigation is required beyond applying the official kernel update.
Description
A use-after-free vulnerability in the Linux kernel's ksmbd SMB2 NEGOTIATE handler was fixed. The flaw involved concurrent SMB2 NEGOTIATE requests on the same connection leading to a race condition where a shared connection state pointer could be freed while still being accessed, causing a use-after-free read. This was confirmed by Kernel Address Sanitizer (KASAN). The fix serializes access to the shared pointer using a connection lock to prevent concurrent access during free and read operations.
References
- nvd.nist.gov/vuln/detail/CVE-2026-72422 (opens in a new tab)
- git.kernel.org/stable/c/0c054227479ed7e36ebccb3a558bc0ef698264f6 (opens in a new tab)
- git.kernel.org/stable/c/16a1ecf39c217e3d164bd32ef2a4f650abc067fa (opens in a new tab)
- git.kernel.org/stable/c/1c89da3baa2b1f269178afa87dc30479b8535776 (opens in a new tab)
- git.kernel.org/stable/c/7470511d085af1c7a043a60e53d52b512d5a10b1 (opens in a new tab)
- git.kernel.org/stable/c/77bb0bbfcc4e777ca653174689e5e363f8ee63d1 (opens in a new tab)
- git.kernel.org/stable/c/c7bef84740d1d57848c74f6f5b996606e43ea4fe (opens in a new tab)
- git.kernel.org/stable/c/d0a469122e7bf8338fec1949fb1e8e1290ed8caa (opens in a new tab)
- ubuntu.com/security/CVE-2026-72422 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-72422 (opens in a new tab)
- git.kernel.org/linus/0c054227479ed7e36ebccb3a558bc0ef698264f6 (opens in a new tab)
- ubuntu.com/security/notices/USN-8781-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8876-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)