CVE-2026-98049: Linux kernel · bpf: zero extend the result of an arena 32-bit cmpxchg
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation 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 for this vulnerability has been implemented in the Linux kernel by adjusting the is_cmpxchg_insn() function to handle BPF_PROBE_ATOMIC mode correctly. Users should apply the official kernel updates that include this patch. Since this is a kernel-level fix, upgrading to a patched kernel version is the recommended remediation. No additional mitigations are specified or required beyond applying the official fix.
Description
A medium severity vulnerability (CVE-2026-98049) in the Linux kernel's BPF subsystem involves improper zero extension handling of a 32-bit compare-and-exchange (cmpxchg) operation on arena pointers. This flaw arises because the is_cmpxchg_insn() function only matches BPF_ATOMIC mode, missing zero extension adjustments needed for BPF_PROBE_ATOMIC mode. The issue has been resolved by adjusting the matching logic to include BPF_PROBE_ATOMIC. The vulnerability affects specific Linux kernel versions listed and has no known exploits in the wild.
References
- ubuntu.com/security/CVE-2026-98049 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98049 (opens in a new tab)
- git.kernel.org/stable/c/4814ed6406f3493bd554ad046da5f7fc04833571 (opens in a new tab)
- git.kernel.org/stable/c/1c1b476d43a8b6c9bc04600369dd8cc39950d98e (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-98049 (opens in a new tab)