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A public disclosure detailed eight OpenZFS on Linux vulnerabilities, tracked as OZ-1 through OZ-8, that weaken authorization checks and expose multiple import-time parser bugs. The report says pool-control ioctls improperly trust namespace-local CAP_SYS_ADMIN from unprivileged user namespaces and containers when /dev/zfs is accessible, allowing host pool operations from confined environments. Reported parser flaws include out-of-bounds reads and writes, a controlled heap overflow, a stack overflow, unbounded traversal, and a cache-destroy hang; OZ-4 was demonstrated as both a container-to-host-root exploit in a research VM and a reliable host-kernel denial-of-service path via malicious OCI images on TrueNAS SCALE and IncusOS.
Testing cited in the disclosure covered IncusOS, TrueNAS SCALE, Proxmox VE, and Unraid, while noting that a tested RHEL 10.2 configuration with OpenZFS 2.2.10 plus SELinux/STIG/FIPS blocked OZ-1 and OZ-2. The report said all OZ findings remained unfixed in upstream master as of 2026-07-24, except for OZ-7, which had an open contested pull request. Separately, Linux kernel documentation notes that kernel CVE assignment is conservative, generally tied to fixes already merged into supported stable trees, and excludes unsupported versions and distribution-specific issues, leaving downstream vendors and users to determine applicability and prioritize full released updates over cherry-picking individual fixes.
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On 2026-08-16, Erica Windisch publicly disclosed a broad set of OpenZFS on Linux vulnerabilities via fulldisclosure and oss-sec. The disclosure covered authorization flaws and multiple parser/runtime bugs, including OZ-4 as a demonstrated container-to-host-root exploit path in a research VM.
The report says CERT was notified about the OpenZFS on Linux vulnerabilities on 2026-08-12. This marks the formal notification of the findings prior to public disclosure.
The disclosure states that all reported OZ findings were still unfixed in upstream OpenZFS master as of 2026-07-24, with only OZ-7 having an open contested pull request. This established the upstream remediation status at the time of the research.
Erica Windisch's research into OpenZFS on Linux vulnerabilities was conducted from 2026-07-17 through 2026-07-25, and the report was updated on 2026-07-25. The work identified authorization flaws and multiple parser/runtime issues labeled OZ-1 through OZ-8.
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Two Linux kernel use-after-free vulnerabilities were disclosed in packet-filtering components, exposing systems to local privilege escalation. **CVE-2026-23111** affects the `nftables` subsystem and stems from an inverted conditional in `nft_map_catchall_activate()` that mishandles catchall elements during transaction aborts, leaving a dangling chain reference. A public technical write-up and working exploit showed the bug can achieve root privileges with high reliability on Debian Bookworm, Debian Trixie, Ubuntu 22.04 LTS, and Ubuntu 24.04 LTS by corrupting chain reference counts, bypassing KASLR, leaking heap addresses, hijacking control flow with a fake `nft_expr_ops` structure, and executing a ROP chain that calls `commit_creds(&init_cred)`. The exploit also uses `switch_task_namespaces()` to break out of namespaces and containers. A separate flaw, **CVE-2026-23412**, affects the Linux kernel’s BPF netfilter link implementation in `nf_bpf_link.c`, where synchronous deallocation of `bpf_nf_link_lops` allowed concurrent `nfnetlink` hook enumeration to access freed memory during BPF link destruction. Researchers reproduced KASAN slab-use-after-free crashes in `nfnl_hook_dump_one` on kernel `6.14.0` and said the bug could be exploited through heap spraying and function-pointer hijacking in the `kmalloc-192` slab cache. The issue was introduced in `6.4-rc1` and fixed in `7.0-rc5` by commit `24f90fa3994b`, which switches to RCU-deferred freeing, while the `nftables` bug was patched upstream by commit `f41c5d1`; administrators were urged to deploy patched kernels promptly.
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Aug 25, 2026