CVE-2026-23111: exploiting and detecting a nftables UAF born from a security fix
Source Reddit ExploitDev
Mentioned vulnerabilities
Not known to be exploited.
Data as of 31 Oct 2026, 20:20 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
Public on cve.org; its publication date is not in this record
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.
What to do
AI-suggested
Patch versions have been released for affected GKE Ubuntu and Container-Optimized OS node pools. Users should upgrade their node pools to the specified patched versions or later to remediate the vulnerability. For GKE on AWS, Azure, and VMware environments, patch and severity information is pending; monitor vendor advisories for updates. Bare metal GDC users require no action as they are not affected. Avoid insecure configurations such as setting seccomp Unconfined profile or allowing CAP_NET_ADMIN in Autopilot clusters to reduce risk.
Discussion
CVE-2026-23111 is a use-after-free vulnerability in the Linux kernel's nftables subsystem, introduced by a flawed security fix for a previous vulnerability (CVE-2023-4244). It affects Container-Optimized OS nodes and can lead to privilege escalation. Google Kubernetes Engine (GKE) Standard clusters are impacted, while Autopilot clusters are not vulnerable by default unless specific insecure configurations are used. Patch versions have been released for Ubuntu node pools and Container-Optimized OS node pools on GKE. Other GKE environments (AWS, Azure) and VMware are pending patch and severity updates. Bare metal GDC software is not affected as it does not include an OS. The vulnerability is rated high severity. Detection techniques focus on monitoring behavior rather than payload signatures, applicable even on patched kernels.
r/ExploitDev (opens in a new tab)u/rafael-d-tinoco0 points0 comments
This is part two of a series. Part one was about detecting CopyFail and DirtyFrag - if you missed it, same idea applies here.
CVE-2026-23111 is a use-after-free in nf_tables, reachable from an unprivileged user namespace. The bug is a single inverted character introduced by the commit that fixed CVE-2023-4244 - a security patch that quietly planted a new reference-counting flaw and rode the backport train into every stable LTS branch for two years.
The full exploit is published at:
KASLR leak, arbitrary read, runtime kernel structure traversal, and a ROP chain that lands you at uid=0 with nothing hardcoded. The repository also covers prior work from Exodus Intelligence and FuzzingLabs and what this build adds on top of it.
The Medium post is about something different: why detecting the payload is the wrong problem to solve, and what you watch instead to catch this reliably - on vulnerable and patched kernels alike, including the failed attempts that most tools never see.