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A use-after-free write flaw in the Linux kernel's Netfilter nf_tables/nftables subsystem, tracked as CVE-2022-32250, can allow a local attacker to escalate privileges to root. The defect is triggered by supplying a non-stateful lookup or dynset expression as a subexpression in an NFT_MSG_NEWSET operation: the expression is bound to a set, then freed without removal from the set's binding list, leaving a stale reference that can be used for memory corruption.
Researchers demonstrated exploitation on Ubuntu 22.04 running kernel 5.15.0-27-generic, using user_key_payload and POSIX message queues to leak heap and KASLR addresses before overwriting modprobe_path for root execution. Exploitation requires the ability to create user and network namespaces. The upstream fix, committed as 520778042ccca019f3ffa136dd0ca565c486cedd, moves NFT_EXPR_STATEFUL validation into nft_expr_init so unsupported expressions are rejected before allocation and binding can create the dangling reference.
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A technical write-up demonstrated exploitation on Ubuntu 22.04 with kernel 5.15.0-27-generic, using heap and KASLR leaks followed by a controlled write to overwrite modprobe_path. The write-up stated that full exploit code was published in a GitHub repository for educational and research purposes.
The Linux kernel netdev tree fixed the issue in commit 520778042ccca019f3ffa136dd0ca565c486cedd. The fix prevents unsupported non-stateful expressions from being allocated and bound as set subexpressions.
EDG reported CVE-2022-32250, a use-after-free write flaw in the Linux Netfilter nf_tables subsystem that can enable local privilege escalation to root. The flaw leaves a stale set binding when non-stateful lookup or dynset expressions are rejected during NFT_MSG_NEWSET processing.
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Researchers detailed exploitation of **CVE-2023-31248** in the Linux kernel's `nftables` subsystem, showing how a chain lookup flaw can let local attackers gain root privileges. The bug exists because `nft_chain_lookup_byid` did not verify whether a chain was still active through `genmask` checks, allowing rules in a batch transaction to reference chains deleted in the same batch. That logic error can trigger a **use-after-free** when rule deletion in the control plane races with asynchronous transaction-worker cleanup, creating a path to reclaim freed memory and corrupt kernel objects. The write-up demonstrates an exploit on **Ubuntu 23.04** with kernel `6.2.0-20-generic`, using heap sprays and information leaks to recover kernel text and heap addresses before forging `nftables` structures and building a ROP chain that invokes `prepare_kernel_cred` and `commit_creds` to obtain a root shell. Researchers said kernels before `6.2.0-26-generic` were vulnerable, while upstream fixes added `genmask` validation to chain-by-ID lookups so inactive chains cannot be referenced. The same research also described a separate dormant-state chain hook deactivation bug that can trigger kernel warnings but was assessed as not practically exploitable and patched by blocking repeated dormant-state toggles within a single batch.
Jun 29, 2026
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.
Jun 29, 2026
A use-after-free flaw in the Linux kernel's Netfilter nftables `nft_pipapo_walk` function, tracked as **CVE-2023-6817**, can allow a local attacker with `CAP_NET_ADMIN` to crash a host, disclose information, or elevate privileges. The defect allowed inactive PIPAPO set elements to be processed and deactivated twice during a set walk, leading to a kernel crash; it carries a CVSS v3.1 score of 7.8. Linux kernel commit `317eb9685095678f2c9f5a8189de698c5354316a` fixes the issue by verifying that an element is active before invoking the iterator callback. Red Hat issued fixes for affected RHEL 8 `kernel` and `kernel-rt` packages; systems with unprivileged user namespaces enabled may let unprivileged users obtain the required capability. OpenShift Container Platform inherits the affected code through RHCOS, but Red Hat rates impact as Low because its namespace model prevents containers from acquiring the capabilities needed to exploit the flaw.
Aug 26, 2026