CVE-2026-98021: Linux kernel · net: reject oversized tx_queue_len at netlink parse time
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 6.8 Medium.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation 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
The vulnerability has been resolved in the Linux kernel by enforcing the tx_queue_len cap at netlink parse time. Attempts to set oversized tx_queue_len values are now rejected with an -ERANGE error and an "integer out of range" extended acknowledgment message before any device state is modified. Users should upgrade to a fixed kernel version that includes this patch. No additional mitigation is required once the fixed kernel is deployed.
Description
A vulnerability in the Linux kernel net subsystem allowed oversized tx_queue_len values to be assigned directly to network devices via netlink messages, bypassing the intended maximum cap. This could cause oversized ring buffer allocations in pfifo_fast, tun, and tap devices. The issue was fixed by enforcing the maximum tx_queue_len cap at netlink parse time, rejecting out-of-range values before device state modification.
References
- ubuntu.com/security/CVE-2026-98021 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98021 (opens in a new tab)
- git.kernel.org/stable/c/1aa9e143bf51405665a793d4cc925e1c4f0c5922 (opens in a new tab)
- git.kernel.org/stable/c/a638a2625aa83160a394abe8e8b2e524a80c771b (opens in a new tab)
- git.kernel.org/stable/c/2fd0880f0272ec022906a05587fd91416ebecc38 (opens in a new tab)
- git.kernel.org/stable/c/45ca9f59b6c7ea70e0a17054902b8a556913db34 (opens in a new tab)