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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.
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Red Hat issued RHSA-2024:0897 for affected RHEL 8 kernel packages and RHSA-2024:0881 for RHEL 8 kernel-rt packages, fixing CVE-2023-6817.
Florian Westphal authored a patch to skip inactive nftables pipapo set elements during set walks, preventing their double deactivation and resulting kernel crash. Xingyuan Mo reported the issue.
Red Hat released RHSA-2024:1367 for RHEL 8.4 Advanced Mission Critical Update Support kernel packages and RHSA-2024:1382 for RHEL 8.4 Telecommunications Update Service kernel-rt packages.
Red Hat fixed affected RHEL 8.2 Advanced Update Support kernel packages in RHSA-2024:1268 and Telecommunications Update Service kernel-rt packages in RHSA-2024:1269.
Pablo Neira Ayuso committed upstream Linux commit 317eb9685095678f2c9f5a8189de698c5354316a, which checks whether an element is active before invoking the nft_pipapo_walk iterator callback.
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**CVE-2023-3390** is an important-severity use-after-free flaw in the Linux kernel's Netfilter/nftables subsystem. Improper handling of named and anonymous sets in batch requests can allow a local attacker with `CAP_NET_ADMIN` to read and write arbitrary kernel memory, potentially causing denial of service or escalating privileges. Red Hat rates the vulnerability **CVSS 7.8** (`AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`). Unprivileged user namespaces can enable local unprivileged RHEL users to obtain the capability needed for exploitation. Red Hat released fixes for affected RHEL 8 `kernel`, `kernel-rt`, and `kpatch` packages, with updates issued from September 2023 through March 2024. OpenShift control-plane hosts contain the affected component, but Red Hat assesses container exploitation risk as low because OpenShift namespace controls prevent containers from obtaining the required capability.
Aug 26, 2026
**CVE-2024-27397** is a use-after-free flaw in the Linux kernel's `netfilter`/`nf_tables` subsystem. During control-plane transactions, a set element with a timeout could expire before the transaction completed because affected set backends did not use a transaction-start timestamp. A local low-privileged attacker could potentially crash an affected host or elevate privileges; the vulnerability affects code introduced in Linux kernel 4.1. The issue is fixed in Linux kernel 6.7.5, 6.8, and later stable releases. Red Hat issued corrected `kernel` and `kernel-rt` packages for multiple RHEL 8 and 9 streams and rates the flaw Moderate, while CVSS assessments range from 7.0 to 7.8 depending on assumed attack complexity. Organizations should deploy current vendor kernel updates rather than cherry-picking patches; non-containerized RHEL 8 systems may temporarily disable user namespaces, but this mitigation must not be used on OpenShift because its containers require user namespaces.
Aug 26, 2026
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.
Aug 26, 2026