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VulnerabilityPublished Updated

CVE-2026-64032: Linux kernel · bridge: mcast: Fix a possible use-after-free when removing a bridge port

Affects Linux kernelSource GCVE Database

0
Authoritative record:CVE-2026-64032· High 7.8

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

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 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 26.04 LTSlinuxpkg:deb/ubuntu/linux@7.0.0-28.28?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-28.28
Fixed in
  • 7.0.0-28.28
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws@7.0.0-1009.9?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1009.9
10 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure@7.0.0-1009.9?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1003.3 – 7.0.0-1009.9
10 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde@7.0.0-1008.8?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1003.3 – 7.0.0-1008.8
4 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp@7.0.0-1008.8?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1008.8
Fixed in
  • 7.0.0-1008.8
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke@7.0.0-1003.4?arch=source&distro=resoluteOther threatsAffected
  • <7.0.0-1003.4
Fixed in
  • 7.0.0-1003.4

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

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