CVE-2026-98104: Linux kernel · net/sched: cls_u32: fix duplicate handle when node ID pool is exhausted
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 13:47 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 adds proper exhaustion checks and returns errors when the node ID or handle pools are exhausted, preventing duplicate handles. Users should update to patched kernel versions that include this fix. Since the vulnerability is resolved, no additional mitigation is required beyond applying the official patch.
Description
A vulnerability in the Linux kernel's net/sched cls_u32 component allows duplicate handles to be created when the node ID pool is exhausted. This occurs because the function gen_new_kid() returns a fallback handle instead of an error when ID allocation fails, causing handle collisions in the hash table. This breaks handle uniqueness and can lead to incorrect removal and reuse of live nodes. The issue affects configurations with CONFIG_NET_SCHED and CONFIG_CLS_U32 enabled and can be triggered by adding a large number of u32 filters or proto entries. The vulnerability has been resolved by adding proper exhaustion checks and returning errors when the node ID space is exhausted.
References
- ubuntu.com/security/CVE-2026-98104 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98104 (opens in a new tab)
- git.kernel.org/stable/c/feab9261b537df4ebb8350e4779bc185373059fd (opens in a new tab)
- git.kernel.org/stable/c/f594f04268d01c5fdc975f3f51fc219ea2159ac6 (opens in a new tab)
- git.kernel.org/stable/c/d7e7e98d23f42a92d9ab7e36302bd96bd9b33b5f (opens in a new tab)
- git.kernel.org/stable/c/6890e28840bae4f6805e8de981c4ec8e12a4e064 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-98104 (opens in a new tab)
- git.kernel.org/stable/c/84223baf21bc9b008444ae9bc38d5fb91fe00b9d (opens in a new tab)
- git.kernel.org/stable/c/f4ee13ed7f7b22dcd8287fcf477ae37bd84567da (opens in a new tab)