CVE-2026-64032: Linux kernel · bridge: mcast: Fix a possible use-after-free when removing a bridge port
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-186.196~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 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 5.15.0-186.196~20.04.1, 5.15.0-184.194~20.04.1, 5.15.0-1064.66~20.04.1 +17
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 19 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@7.0.0-28.28?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@7.0.0-1009.9?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@7.0.0-1009.9?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@7.0.0-1008.8?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp@7.0.0-1008.8?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke@7.0.0-1003.4?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 prevents enabling or disabling per-port multicast contexts improperly when per-VLAN multicast snooping is enabled. Users should update to the fixed kernel versions as provided by their Linux distribution vendors. No additional mitigations are indicated by the vendor advisory.
Description
A use-after-free vulnerability was discovered and fixed in the Linux kernel's bridge multicast snooping implementation. The issue arises when both per-port and per-{port, VLAN} multicast contexts are enabled simultaneously on a bridge port, leading to improper disabling of the per-port multicast context upon port removal. This flaw can cause a use-after-free condition, potentially resulting in system crashes or privilege escalation. The vulnerability affects multiple Linux kernel versions and has been addressed in updated kernel releases.
References
- ubuntu.com/security/CVE-2026-64032 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-64032 (opens in a new tab)
- git.kernel.org/linus/4df78ff02629c7729168f0696a7a2123c389818d (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8593-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8603-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8610-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8618-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8620-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8620-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8620-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8620-4 (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-8668-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)