CVE-2026-97939: Linux kernel · ipmr: account multicast table and route memory
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 14:05 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 25 Sep 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
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 fix is available that properly accounts for mr_table allocations in memory control groups and marks multicast forwarding cache entries for memory accounting. Users should apply the official Linux kernel updates that include this fix. Since this is a kernel-level memory accounting issue, upgrading to patched kernel versions is the recommended remediation.
Description
A vulnerability in the Linux kernel's IP multicast routing (ipmr) subsystem allowed a network administrator in a user+net namespace to create many multicast routing tables without proper memory accounting. This caused unreclaimable slab memory growth on the host. The issue was resolved by charging mr_table allocations to memory control groups (memcg) and marking multicast forwarding cache (MFC) caches for accounting. Unresolved MFC entries remain uncharged but are bounded and expire after 10 seconds.
References
- ubuntu.com/security/CVE-2026-97939 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-97939 (opens in a new tab)
- git.kernel.org/stable/c/d0a2e2a4ee6bfe51e398bfb6921a7d0f4c26bc1c (opens in a new tab)
- git.kernel.org/stable/c/b7ee18725f2292ab554aa96a101ae42d45f008bd (opens in a new tab)
- git.kernel.org/stable/c/0264b3ee09b118fec8a5471b4ca288f8ab84722f (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-97939 (opens in a new tab)
- git.kernel.org/stable/c/ec1c6140394ee87127479bc500a3158b125bf07a (opens in a new tab)