CVE-2026-98631: Linux kernel · xsk: Use a 32-bit compare in xsk_map_gen_lookup
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 6.8 Medium.
Data as of 28 Oct 2026, 01:28 UTC
CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/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: xsk: Use a 32-bit compare in xsk_map_gen_lookup xsk_map_gen_lookup() loads a u32 key and compares it with max_entries using BPF_JMP_IMM. BPF immediates are sign-extended to 64 bits, so a max_entries value of 0x80000000 or higher becomes a threshold larger than every zero-extended 32-bit key. An out-of-range index then skips the bounds check and the generated lookup reads past xsk_map[]. Compare with BPF_JMP32_IMM so the check stays in 32-bit unsigned range.
References
- ubuntu.com/security/CVE-2026-98631 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98631 (opens in a new tab)
- git.kernel.org/stable/c/227ec890559e922e235eb543646e3bf0bd8269b0 (opens in a new tab)
- git.kernel.org/stable/c/70504de0bb627848667207bec7ccfd647deb8814 (opens in a new tab)
- git.kernel.org/stable/c/36461e58f88a1b723f86693f437ac12e60ff4363 (opens in a new tab)
- git.kernel.org/stable/c/c6d5c582d55a8f229d75e98d62eaa065b0deb18d (opens in a new tab)
- git.kernel.org/stable/c/123f90f394ca404ab8796a7c8072ff7fa5b65a9c (opens in a new tab)
- git.kernel.org/stable/c/b5c0cff0c5331582ab01c4c423731453a8381acc (opens in a new tab)
- git.kernel.org/stable/c/3c1e0a4bc156b8d5c5772dbc76b9ea74dce5ca24 (opens in a new tab)
- git.kernel.org/stable/c/11d9be35c1f4233798e99be98bc474f83a254c6c (opens in a new tab)