CVE-2026-64537: Linux kernel · bridge: cfm: reject invalid CCM interval at configuration time
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, 14:05 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% 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 +41
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
An official fix is available that validates the CCM interval at configuration time and rejects invalid values. Users should apply the updated Linux kernel versions that include this patch to mitigate the issue.
Description
A vulnerability in the Linux kernel's bridge component (CVE-2026-64537) was resolved by validating the Continuity Check Message (CCM) interval at configuration time. The flaw allowed an invalid CCM interval to cause a worker function to execute in a tight loop, allocating memory until exhaustion (OOM). This could lead to denial of service conditions. The fix constrains the CCM interval to a valid range and rejects starting CCM transmission if the interval is not properly configured.
References
- ubuntu.com/security/CVE-2026-64537 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-64537 (opens in a new tab)
- git.kernel.org/linus/f3e02edd8322b31b8e6517faa6ba053bf29d1e26 (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)
- ubuntu.com/security/notices/USN-8888-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8889-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-3 (opens in a new tab)