CVE-2026-98047: Linux kernel · bpf: Check ancestor frames for rbtree callbacks
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 14:05 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 11% 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 has been implemented to address this vulnerability by enhancing the verifier to check all active frames for rbtree callbacks, preventing bypass of callback restrictions. Users should apply the official kernel updates that include this patch to affected versions. No additional mitigation steps are indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's BPF subsystem involving rbtree callbacks was resolved. The issue arises because the bpf_rbtree_add() function invokes its comparator while holding the root lock, but the verifier only checks the innermost frame for callback restrictions. This allows nested frames to bypass restrictions, potentially unlocking the tree and modifying nodes during insertion, leading to use of stale pointers and memory corruption. The fix involves checking all active frames for rbtree callbacks to enforce proper restrictions.
References
- ubuntu.com/security/CVE-2026-98047 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98047 (opens in a new tab)
- git.kernel.org/stable/c/2410cb2ac0416dd2795a81984c8c73d7250bd8c4 (opens in a new tab)
- git.kernel.org/stable/c/369f4ce734570bdfedaa4b5ca50e2a3f6a892728 (opens in a new tab)
- git.kernel.org/stable/c/b545fa447e09e6844868deb2bee228827fe54d15 (opens in a new tab)