CVE-2026-98622: Linux kernel · net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.7 High.
Data as of 28 Oct 2026, 01:28 UTC
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 18 Oct 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.
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure flow_offload_alloc() returns NULL when the conntrack entry is dying (e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation fails; both are expected under load and neither is a kernel bug. This path runs from softirq on every committed packet, so with panic_on_warn=1 an unprivileged user can panic the box just by racing a conntrack flush against a `tc ... action ct commit` classifier. Reproduced with a custom repro under QEMU: a small, fixed set of UDP flows through `tc filter ... action ct commit` on lo, raced against threads flooding bare ctnetlink CT_DELETE (flush) requests. Hits WARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined into tcf_ct_act() in this build) within ~15s on the unpatched kernel; same setup is clean on the patched kernel. The fix itself is behavior-preserving: both branches already did `goto err_alloc` before and after, only the WARN is removed.
References
- ubuntu.com/security/CVE-2026-98622 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98622 (opens in a new tab)
- git.kernel.org/stable/c/00734f3684fcec42c319bedfe68a5d357c720b53 (opens in a new tab)
- git.kernel.org/stable/c/650787233c2fd6e515a7c5f371019a9fa080ccd2 (opens in a new tab)
- git.kernel.org/stable/c/424ba52c0058deeb940d02cba52eb0aeb288db33 (opens in a new tab)
- git.kernel.org/stable/c/d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a (opens in a new tab)
- git.kernel.org/stable/c/e8fcf3f08834e939b797311742ee72b1e2a08096 (opens in a new tab)
- git.kernel.org/stable/c/af475f599270e59313552e6c6f3af8507da672b8 (opens in a new tab)
- git.kernel.org/stable/c/47abe7a5c4eb53269aca3506446f851572a059a3 (opens in a new tab)
- git.kernel.org/stable/c/d805560ad69cb266d669341ca01e26bffb0d2c67 (opens in a new tab)