CVE-2026-64527: Linux kernel · drm/hyperv: validate VMBus packet size in receive callback
Affects Linux kernelSource GCVE Database
Not known to be exploited · fixed in 5.15.0-1117.124~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 12:55 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 5% 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 +65
Exploitation evidence
Disclosed: evidence found.
CVE published 27 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 addressing this vulnerability is available and included in recent Ubuntu kernel updates. Users should apply the official kernel updates to remediate the issue. No additional mitigation actions are required as the issue is fixed by validating packet sizes in the kernel subsystem.
Description
A vulnerability in the Linux kernel's drm/hyperv subsystem allowed improper validation of VMBus packet sizes in the receive callback hyperv_receive_sub(). This flaw could lead to reading residual data from prior messages due to unchecked memcpy operations, potentially causing information disclosure. The issue affects multiple Linux kernel versions prior to 7.0.0-28.28 and related builds. A patch has been released and is included in recent Ubuntu kernel updates. No known exploits have been reported in the wild. The severity is assessed as medium.
References
- nvd.nist.gov/vuln/detail/CVE-2026-64527 (opens in a new tab)
- git.kernel.org/stable/c/049a6b474823049fe60212f25f26e4b30f44ee8f (opens in a new tab)
- git.kernel.org/stable/c/164dc7bf17609340233c6bf4f66bb7c7008a0511 (opens in a new tab)
- git.kernel.org/stable/c/57d5d697642e05d5dd2d40660817765943dd709f (opens in a new tab)
- git.kernel.org/stable/c/588c84b461393ff1998ac7b97b04f953f642e0df (opens in a new tab)
- git.kernel.org/stable/c/7f87763f47a3c22fb50265a00619ef10f2394b18 (opens in a new tab)
- git.kernel.org/stable/c/c8974d96b6a5496f33dc69a3ce28a7bf5078def4 (opens in a new tab)
- git.kernel.org/stable/c/f5251226551bfec98c4705641b6f94ff1f238d91 (opens in a new tab)
- ubuntu.com/security/CVE-2026-64527 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-64527 (opens in a new tab)
- git.kernel.org/linus/7f87763f47a3c22fb50265a00619ef10f2394b18 (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-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (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)