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A use-after-free flaw in the Linux kernel traffic-control classifier API, tracked as CVE-2022-1055, can allow a low-privileged local attacker to escalate privileges through unprivileged user namespaces. The vulnerability resides in tc_new_tfilter() in net/sched/cls_api.c; Red Hat rated it moderate severity with a CVSS v3.1 score of 7.8, citing high confidentiality, integrity, and availability impact.
Upstream Linux corrected the issue by explicitly resetting Qdisc and tcf_chain pointers before replayed netlink-message processing in tc_new_tfilter() and resetting Qdisc in tc_ctl_chain(). Red Hat issued fixes for affected RHEL 8 and RHEL 9 kernel packages; RHEL 6 and 7 kernel and kernel-rt packages are not affected. As a mitigation for non-containerized RHEL 8 deployments, Red Hat recommends disabling user namespaces, though this is unsuitable for platforms such as Red Hat OpenShift that require them.
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4 events from the most recent confirmed update back to the earliest known activity.
Red Hat issued RHSA-2022:7683 for affected RHEL 8 kernel packages and RHSA-2022:7444 for affected RHEL 8 kernel-rt packages, fixing CVE-2022-1055.
Red Hat issued RHSA-2022:6003 for affected RHEL 9 kernel packages and RHSA-2022:6002 for affected RHEL 9 kernel-rt packages, fixing CVE-2022-1055.
Red Hat issued RHSA-2024:1188 to fix CVE-2022-1055 in RHEL 8.6 Extended Update Support kernel packages and Red Hat Virtualization 4 for RHEL 8 kernel packages.
An upstream Linux kernel patch modified net/sched/cls_api.c to reset Qdisc and tcf_chain pointers during replayed processing in tc_new_tfilter, addressing a use-after-free condition. The patch also reset the Qdisc pointer in tc_ctl_chain.
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**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
**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.
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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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